I have tried to find a decent canned/boxed/concentrated stock, in stores and online, with only the most limited success. MoreThanGourmet products came closest to acceptable. So I use only homemade stock. It's simply too easy (and cheap) to make to use a poor alternative.
For example, every so often, I buy a "family pack" of chicken parts, usually thighs, and toss them in oil and salt and roast them for a bit over an hour in a 400F oven. If I want a few thighs for meals, I set some aside. The rest, I split and put into the pot with celery, onions, and carrots and an herb bouquet from the garden and simmer for four or five hours, and strain. That family pack is generally five or six pounds, and with a third of it held out for meat, the rest makes several 2-cup batches of stock frozen in reusable freezer containers. (There are two of us, and two cups make a good portion for most things.) If I used the whole "family pack," I could have a couple of gallons of stock for maybe seven dollars. I could make even cheaper stock if I used more chicken and had enough bones left over. This is much superior stock than any store product, and it's hardly any work at all, considering that I get two or three chicken meals out of it, also. And the bonus chicken fat (schmaltz) skimmed from the chilled stock is useful.
The herbs come from culinary garden planters out back, and I roughly chop and freeze herbs that won't winter over. I have no prejudice about dried herbs. I just have the fresh and frozen always at hand.
I don't make fish stock ahead. Seafood stocks are too easy to do with trimmings on the spot.
"Kitchen duty is awarded only to those of manifest excellence..." - The Master, Dogen