I don't think anything compares to real drippings but you can buy cheap poultry and beef parts to get the same flavor. Wings, backs, necks, ...well, I don't know of much that's cheap in the way of beef, but a package of beef ribs would go a long way towards great gravy flavor.

Years ago, before so many foodies arrived, the butcher grocer would give me huge meat bones for free.
Last time I asked for some, they were priced at $15. I gulped, said nothing, and never asked again.

How did the beef or chicken or whatever get cooked to make leftovers?
There is your source of drippings and stuff to make gravy.
Canned broth will just make "thickened broth"...not gravy.

If you're caught short, what I do is use a really good "jus de roti" cube added to some water, add equal part red wine, let it reduce then add a knobof butter at the end.

--Keep a bottle of "Kitchen Bouquet" on hand. It's a browning and seasoning sauce that will work well in conjunction with bouillon. Even a little coffee or a little instant coffee crystals will give beef bouillon a deeper flavor. Dried mushrooms (pulverized) is another good add-in. Or try a vegetarian mushroom gravy made with fresh mushrooms.

--You can brown some finely chopped onion in a little fat, add 1/2 to 1-teaspoon of Kitchen Bouquet, boiling water and beef bouillon. Use cornstarch and water to thicken.

--When you do have broth or extra drippings, freeze a portion in an ice cube tray (it doesn't have to be a full tray). Pop them out and keep in the freezer in a container/zip-lock bag/vacuum-sealed bag - whatever storage method you like. The easiest way to accumulate extra juices is to bake meat in oven bags. I had over 2 cups of broth from the Thanksgiving Turkey Breast. I make vegetable broth, as well as meat broth, and store it in cubes in the freezer.

--When you use canned broth, be sure to cook it down long enough to reduce the liquid before making it into gravy. The reduction will create more flavor. Swanson Flavor Boost packets are the concentrated version of broth and may be a good pantry item and preferable to dried bouillon packets.

--Check out recipes for making vegan or vegetarian type gravy. That might help you out in a pinch as well.

-Grainlady

I personally, do not like cornstarch thickened gravy...the texture is just off to me. Flour all the way for me.

Maybe if you added some of the meat that you will be pouring it over, diced up to the gravy(cook that a bit before thickening it), that would help add some flavor.

If you like gravy and eat it often, I think it would make sense to make it partly or fully ahead of time. You don't have to do a whole roast- you can get great flavor from skin-on chicken pieces. (Make sure not to buy solution-injected chicken, because it keeps the chicken and drippings from browning properly). Roast until well browned, then add water to the pan to help scrape up the drippings, transfer the whole mess to a pot, and simmer the chicken + drippings for several hours. Strain through a coarse (pasta) strainer to catch the bones and meat but leave the small particles, and refrigerate the liquid. It will separate, stock on the bottom (with the good brown stuff in it) and the fat on top. The chicken fat can then be mixed with butter (good, Irish or European butter if you really want to get serious) for the roux, and then the stock goes back in. Things like sauteed onion, mushrooms or truffle salt, sherry, etc, can boost a mediocre gravy, but nothing comes close to the real thing. It freezes and thaws beautifully, and I'd rather have excellent gravy from a different meat than mediocre gravy from the same meat.

For beef broth, you can add a bit of tomato powder or paste, Worchestershire sauce, soy sauce, tamarind paste, ginger, thyme, oregano, garlic, chili sauce, balsamic vinegar, red wine, or any number of other flavorings, depending on how you will be using it. I frequently add dried mushrooms, as they have an intense flavor, and you can soak them in the broth that you will be using. Note that I do not add all the flavorings to the same sauce - I make different combinations of the spices.

I frequently use a Japanese combination which includes Ponzu sauce, ginger, garlic, chilies, and sesame oil.

Lars

And with chicken a cream sauce using half cream and half chicken broth is a great sub for gravy.

If tarragon and coriander aren't spices you've tried adding, I would recommend them. Tarragon is very powerful but I've never been eating dinner and thought "I put too much coriander."

A few fat cloves of garlic roasted till it's the consistency of applesauce can do a lot for gravy also. Easiest to add with the flour and butter, at the thick stage before thinning with the broth or whatever liquid.

I would also marry 2 of the already-given suggestions, by sauteing minced onion WITH a small piece of the meat that's for dinner, a little Worcestershire sauce until you get a blackening started on the bottom of the pan. Deglazing that into the gravy will definitely add color and flavor.