A Few Questions.

My wife is a professional artist and since retiring I have become her "graphics guy". We have close to 200 different notecard designs that we print and sell. We try to keep an inventory of 10 of each design on hand. Some weeks I need to print six or seven hundred cards of varying designs. For several years I was using an HP 3600n Laserjet printer which worked OK but I always felt that the toner was a little pricey. This summer the 3600n died in the middle of a busy period and I ended up making an emergency purchase of an HP Laserjet Pro 451dn. The new HP has been a disappointment, the toner is even more expensive, the cartridges are smaller and the printer is slower. Which brings me to my questions:
Is there a more economical way? Should I be using something other than a laser printer? If not can anyone have a recommend a better unit ?
I have tried using remanufactured cartridges but half the time they end up streaking or not producing the quality we require. Thanks!