Check out Midsouth Shooter's Supply for jacketed bullets.
www.midsouthshooterssupply.com
Check out National Bullet Company as another source for cast pistol bullets.
www.nationalbullet.com
For cast rifle bullets you need to get as picky as your gun is. Try buying minimum size samples from a number of different makers and see which ones actually shoot well in your guns? Choose the shape for what you want them to do. For example, Brother Creeker's 430 grain .459 looks like a good 45-70 game getter to me. When you find "the one" your gun loves, any caster will sell by the 1000 and up without complaint.
Nick