The Internet is your friend. You first have to decide what you want, or think you want, then start searching. It's amazing how much cheaper you can buy things on-line if you are willing to do the leg work (finger work?) As an example- When we redid our kitchen, I found hardware I liked at a local big box store. I then did a google search, and found the exact same brand and model for less than half the price. Even better, there was no shipping cost or sales tax. I've bought everything from tools to nails to hardware, all at considerable discount.

For things that are too big to ship easily, my contractor has been a great source of information. I am building my own house, with the contractor just doing the excavation and concrete work. He knows the best local places to buy construction materials at the best prices, and is willing to pass along this information.

I have found good deals on craigslist and ebay as well. Here in FL, the building industry is very depressed, so you can find bargains if you do enough looking and act quickly. I bought my Nichiha siding for 25 cents on the dollar, and the trim for 34 cents on the dollar.

I was recently researching kitchen hoods, and found great prices on ebay. Pretty much everything is available much cheaper than local retail.

I am shopping ebay for vintage lighting fixtures to use in key areas. I bought a pair of antique porcelain light fixtures for the bathroom for $60. Reproduction ones that are similar run $160 each, or $320 for a pair! I plan to replace the 'guts' of the fixtures to ensure they are safe and up to code.

Looking for bargains takes some know-how and can be time-consuming, but for me it is the thrill of the hunt, as well as saving a few bucks.

wow flgargoyle, I wish I could find that Nichiha deal here in NC.

Check to see if you have a Habitat for Humanity Restore in your area. I found a utility sink to use in our garage complete with plumbing fixture in fabulous condition for $35. I plan to continue to stop in every few weeks as their inventory changes. Used stuff may not be ideal everywhere, but there have to be a few places where it would be acceptable. They also had many doors and shutters with character. I was so tempted to buy a few to use as headboards. Good luck!

While we used Ferguson for most of our plumbing...I was astounded at the cost of our freestanding claw foot tub. Our builder had speced a jetted tub with a surround...but I wanted freestanding. Found one online at Vintage Tub and Bath for 1/2 the cost! They were awesome to work with, I faxed my plans, they told me all of the plumbing parts I would need to order. They don't charge shipping, and even held it until the builder was ready for it. Our builder wasn't thrilled about using an online vendor, but couldn't find a thing to complain about...and the tub is beautiful.

I had a quite generous lighting allowance, but alas, I also fell in love with several very pricey fixtures for some of the main rooms, especially my foyer, outside fixtures, kitchen island lighting, and DR chandy. I pretty much blew it on just those. No worries, I found some lovely fixtures on Overstock for my children's rooms, a really gorgeous fixture for my master bath, and even some nice, well-made sconces for my powder room. VERY inexpensive!

Bosch has some amazing rebates at the moment - check out AJmadison. I don't need new appliances for 6 months, but I'm buying them now ;)

I am setting up my own sole proprietorship (interior decorating) to secure designer discounts & for access to designer-only lighting options at a savings (some companies are to the trade only). My SIL did this & saved a bundle. It costs very little to set up & will pay for itself many times over.

SIL also uses it for Pottery Barn, RH, Ballard, etc.

Also, there was a similar post not that long ago:

Here is a link that might be useful: Best websites for find deals while building your home?

I guess it also depends on how "high end" you will be going for your fixtures, etc. Sears was our "friend" during our build, good sales around Thanksgiving and Christmas, we bought all our appliances through them, they stored them for us until the house was ready....then our local sears store delivered them!