Being a new veggie gardener, the easiest and cheapest for me have been.....

Looks like you are in zone 9 so similar conditions to what I have.

Herbs

Basil...the plants are inexpensive and they are easy to start from seed. I have them all over.

My chocolate mint and pineapple sage from last year are still growing like crazy. My oregano and thyme that I planted this year seem to be following suit as well. Rosemary grows like a weed year round here.

Also, summer squash/zucchini has been really easy for me and grows very quickly from seed. The seeds are really inexpensive and can last for years. It's also very productive. I have a lot of varieties growing cause it's so quick and easy to start from seed.

Radishes are easy in the cooler weather.

Okra has been really easy for me in the summer. It also grows fast from seed.

Hot peppers are pretty easy in the hot weather.

Tomatoes can be reletively easy.

My most challenging plant so far as been eggplant. I tried it last year and this year and have yet to get an eggplant. All the blossoms fall off.

I use DE powder around all of my containers and it is pretty good at keeping all manner of crawling bugs out. The only thing I've had trouble with is caterpillars since the moths fly onto the plants, but they are easly taken care of with BT.

I've made a lot of mistakes starting out so if those plants work for me, they will probably work for anyone.

Ania

With few exceptions, I've found that bush beans and C. moschata winter squash (butternuts and their relatives), require little preparation and less attention before harvest.

Tomatoes take only slightly more care.

I have found the easiest vegetable to grow to be the turnip. I have always had excellent germination rates, and they grow quite quickly.

The next easiest I have found would be zucchinis. You get a ton of fruit with little to no effort.

Bang for your buck? I'd say banana peppers and zucchini.

Squash (zukes and summer), lettuce, radish, celery, tomatoes and cilantro! -cass

First year gardener and I would say:
Zuchinni
Tomatoes
Herbs (chives, basil, mint)
Arugala

Here is a link that might be useful: first year gardener blog

Garlic has always been easiest for me...and cheap too. I save my own bulbs every year.

As a second year gardener, both years lettuce has never failed me. I really like lettuce. It's ready to harvest very early on in the growing season, and it is gratifying because it is so successful.

This year spinach was also very easy to grow. My cucumbers were very successful last year and looking great this year. I am conning my hubby (he hates garden work) into building me a trellis for my cukes this year. He's taking the job so seriously. He keeps coming home from work telling me about different trellis designs he's read about online. It makes me wonder how much work he is doing.

I didn't grow beans last year, but I am this year, and they are looking good. In one of my bean patches, I am having a slight bug problem, but Captain Jack and his Dead Bug Brew appear to be taking care of the matter.

My peas have been difficult. Despite starting early, I only got three pea plants to germinate. Then I accidentally broke one with the hose. I bought pea plant seedling from local farmer's market to replace it. Also, squash has been difficult for me. I am either not pollinating correctly or I don't have enough calcium in the soil. I am hoping it is the first problem because I can fix that problem much more easily this growing season.

My herbs were a challenge to get started, but once they established themselves, it's been smooth sailing.

Garlic, definitely. A whole head often costs $0.25 around here, and you can plant the individual cloves to get more heads (one per clove). After that, I'd say lettuce, radishes and tomatoes. I understand that squash is really easy too, so I've heard, but my plants never produce the tons of produce that I've heard legends about.

Hands down it's Swiss Chard for me. I grow the rainbow chard, and it's cut and come again from the end of June until the hard freeze in Novemeber. I get wonderful chard all season long from one seed. It's my new favorite vegetable.

I'll also chime in and say garlic. I never got around to planting last fall. However, a perfect block of garlic volunteered where I grew it last year. Apparently some of the cloves came off when I was harvesting. Aside from throwing some water at them now and then, I did absolutely nothing for them, and got a dozen or so, larger-than-market-size heads. Other alliums tend to be easy as well insofar as they tend not to suffer from pests, and don't need much in the way of fertilizing, pruning and so on.

Leeks and fennel - expensive in the store, but easy to grow, so I consider them to give good bang for the buck.

Tomatoes - easy if you are buying plants. A considerable amount of work to start indoors from seed. Same thing with peppers.

Pole beans - in my 6 or so years of growing them, they have been non-fussy, don't suffer much from pests, and I always get a ton of beans.

Kale - very hardy plant and versatile in the kitchen.

Second the comment about chard--I love it, and it produces all season long from 1 seed. That's a lot of veggie for little investment. Same thing with zucchini and butternut squash. Tomatoes are very easy, too--a little fussier about the watering as they are fruiting. Beans are another easy, productive crop.

Garlic is easy if you're very patient (about 8-9 months for me). And it is one of those things that you can just buy from the store, break up and plant. Zucchini, yellow squash, and other summer squash is easy. But I do buy the seeds. I don't know how well seeds from the store would do with those things. Like others have said, tomatoes are easy once you have the plants. Romaine lettuce has been easy for me, but not iceberg. I have yet to get a real head of lettuce from an iceberg seed. Bush beans are also really easy for me. I have grown butternut squash from seeds in a storebought butternut. I got two butternuts off of two vines. I bought seeds this year.

My general feeling about buying seeds verses taking them from storebought veggies, is that it just isn't worth it to try to cut costs there. Seeds aren't that expensive and aside from not really knowing what will come from seeds in the grocery store, my own experience is that you usually get a much lower yield. And for all the time that it takes to grow things, I'd rather grow vines/plants that I can be more sure will produce.

the ones a gardener give you, because they have to much :)

Trick question.

Other than timing and space, starting plants from seed is not that difficult.

For me, problems are squash & melons, sometimes cukes - bugs LOVE 'em!

Other than that, quick & easy = lettuce, radish, tomatoe, potatoe, asparagus, strawberries...Garlic, of course. Cheap seeds = this years clearance pch for next year.

I have problems with cukes and squash too, because of the bugs. I would consider zucchini one of the hardest vegetables for ME to grow for that reason!

I agree with comments about garlic being super easy. I have nothing but good luck with it. I also like how it gets planted in the fall here, gives me something to do when I am sad about the growing season being over. There are apparently no Iowa bugs that eat garlic, because I have every bug here and nothing gets my garlic.

Other than that, I would say pole beans and swiss chard are easiest and cheapest. Anything you can direct sow outside, the is a hardy grower, is a good bang for your buck. If I plant pack of pole bean seeds, I get plenty of beans even between the deer and the japanese beetles taking their share.