Just finished a pair of scratch built Baby Flight Streaks (blew up the 1/2-sized plans from an old kit). I've got a Cox reed-valve Killer Bee in one.

What's a good source for small 1/2A sized wedge or "uni-flow" tanks?

You can get the wedge tanks from Brodak (Brodak.com), and then you are on your own for re-plumbing. It's no big deal, put the back end of the tank on the stove and slip the cover off when it gets hot, then re tube to your heart's desire. Cover any holes by swiping a film of solder over them or a tiny plate of brass.

Or, learn to make your own tanks from sheet .005 brass from the hobby store. Again fun to do and not that hard.

Or...... read my Tanks fer Nuttin' article in Flying Models April 2002 for how to convert convenience hand lotion (etc.) bottles to the tank of your dreams. How about a Tetra tank in 1 oz size for 25 cents (the cost of a balloon)?