I bought 1000 rounds of these guys' "blaster" ammo recently, in 9mm:
http://www.freedommunitions.com
At $9 a box, it's cheaper than the steel cased Tula that Wal Mart sells, but comes with brass cases that you can collect and send back for credit with your next order.
I've only shot one box of it so far, but I was pretty happy with the results. Subjectively, it didn't seem to make the gun as dirty as Winchester White Box from Wal-Mart does, I had no malfunctions, and it seemed every bit as accurate as the WWB I'd been using.
Edit: Gun in question is a Gen 3 Glock 17, which is nearly brand new.
That said, ordering from Freedom Munitions was not a perfect experience:
1. I ordered mine on the 11th, and it didn't actually ship until like the 21st. I gather this had to do with massive order volume following the election.
2. Shipping cost $24, which is somewhat understandable, given the weight, but still seems a little high. Given that my order was $169, adding $24 in shipping really soaks up a lot of what you save by buying this way.