Georgia Arms has 180gr FMJ for $9.50/50 that I have used and found to be good ammo.
I have an Excel spreadsheet that I have been working on that shows ammo prices for a lot of vendors. I've included: dealer name, ammo type, cost/box, multiplier factor (for boxes of <50rds), cost/50, cost/500, cost/1000, S&H - added or included in price, and other info like "out of stock", "odd lot pricing", etc. I only included ammo that I buy, i.e., no lead bullets, no frangibles/exotics, etc., only in calibers that I own.
FWIW, the price on 180gr Blazer FMJ at Midway is OK, but Natchez Shooters Supply has 10mm 180gr FMJ Blazer for $11.78/box or $11.08/box for 10+ boxes.
The bad news about 10mm firearms is that there aren't that many to choose from.
The good news is that alot of them are extremely good.
Still made (off the top of my head)
Glock 20, 20C and 29
EAA Witness 10mm
S&W 610 4"
No longer made but easy to find:
Colt Delta Elite & Gold Cup Delta Elite
S&W 610 5" and 6.5"
The Delta Elite, Glock 20C and S&W 610 are flat-out great (I own all 3
). The EAA Witness is pretty good and a good value for the dollar. Shot an SVI Infinity in 10mm that was sweet. Also got to shoot a Bren Ten which was a heck of a piece of work... unfortunately they are hard to find, expensive and kind of flaky in some respects.
You can also have a .40S&W 1911 converted to 10mm... pretty much all you need are a new barrel (or a .40S&W barrel with the chamber reamed) and a heavier recoil spring. Magazines are the same.