Well, 'a lot' isn't quantitative. A lot to me is 60k plus rounds a year. if you're looking at that amount of ammo, you better be looking at a Dillon 1050. 30 to 60k rounds then I would look at a Dillon 550,650, or Pro 2000. Less than 30k a year, Dillon 550 or Pro 2000. The Pro 2000 can have either an auto indexing or manual indexing head.
Faster is more money. Auto indexing is typically more money. Ease of caliber change is more money. Cartridge and bullet feeders are more money. Getting into reloading is an investment into future amounts of ammo. The gear costs a lot, but if you shoot 30k rounds in a year, you essentially payed the gear off.