You really need to shop around for a box. They are all a matter of taste from what I have gathered here. You can go:
Super High End: Snap On, Beta. Never even buy again. It will last you a lifetime. They sell big ones, and small ones and they all have add on sections. You will keep it for ever. The cost is astronomical. Even more so for a weekend warrior!
High end: Mac and top end Craftsman. I'm sure there are others. These will last you forever. Not as flashy or as accepted by some folks in here, but still some of the best. They are far from cheap but are as good as the Snap on IMO.
Weekend warrior style: Middle range Craftsman, CSPS, Stuff from Grizzly, Northern, and various others. They seem to be pretty good but you should know what to look for. Ball bearing full extension slides, good drawers, good casters...... read a few threads and you will find out all you need to know.
Cheap stuff: Some is better than others. Craftsman, HF, Grizzly lower line stuff and others. Costco and Sam's club sell some decent ones every once and a while. I have a very solid box from Costco. I have never seen another like it. I got it cheap too.
Keep a look out for sales. Buy the best you can afford. I would suggest you stay away from the cheap Craftsman stuff. If that's all you can afford, get the HF boxes. They are much better and bigger for the money. Grizzly has sales on their stuff all the time too. If you can stand the green colour, they are not bad. If you must insist on staying USA only, well, start saving! Snap On/Mac boxes ain't cheap but as I said, they will last forever. You can find deals on them on CL and eBay too.
Things you should look for: (I'm sure others will add to this)
Double walled sides.
Strong drawers. (Try to twist them)
Smooth action on the slides.
Easy locking drawers.
A good lock on the entire thing.
Easy to roll casters with locks.
Well mounted handles. (Grab them and pull, if the side distorts any it will never work when full of tools.)
A size that fits where you want it to fit yet is bigger than what you think you need.
Cost. As I said, deals can be found if you are willing to wait.
Lastly, no matter what you buy, don't let *some* of the people on here tell you that you bought a crappy box. If you like the cheap friction slide Craftsman box, then buy it and be happy! If I knew then, what I know now, I doubt I would have gotten the one I did. I would have likely gotten the HF box (in yellow!) or the Grizzly of the same style. (I don't mind the green It reminds me of Aston Martin for some reason.) If I had unlimited funds....well....Beta all the way!!