+1 for Georgia Arms. Nice guys.
http://www.georgia-arms.com/
These guys will take your old brass and reload it; I've had good luck with the .357 and .38 reloads, but the .45 Long Colts are a bit smoky. They also sell new ammo too, and free shipping if you buy enough.
http://www.bullseyeshootingsupplies.com/default.aspx
A lot of guys in the gun forums rave about ammoman, but I have no experience. Prices seem nice.
http://www.ammoman.com
Here's page with nothing but ammo deals:
http://gun-deals.com/ammo.php