OP, unless you're commited to having the rear pockets most jerseys come with, you can find decent shirts a lot of places....
Even (GASP!) Wal-Mart!
Check out Starter's 'Dri-Star' line of shirts, long- and short-sleeve. I have a drawer full of them -- about $10-15 each, so if they go to sh**, you're not out much (and as a measuring point, none of them are less than 2 years old, one is about 6-7, and they get a LOT of summer wear!).