Don't even think about it!
First, in some instances where a major component needs to be replaced (not normal consumables) the replacement price can go in to the tens of thousands of dollars. Like Slammer eluded to, "Do You Feel Lucky?"
Secondly, if you are paying a per page click charge, your pricing is much easier. You know exactly what each page costs you. Without it, you are just shooting in the dark. For example, your technical specifications on your toner may say you should get 10,000 images per cartridge, your drums 50,000 images, your fuser, 40,000 images, etc. But, are you really? Have you clocked it yourself? Those yields are "estimates" taken at 10% coverage on an 8 1/2 x 11 sheet. Oh, and that one component that needed to be replaced that is not part of the normal consumables, yes, the one that never should have to be replaced. You remember, the one you had to stroke a $15,000 check for? How are you going to compute that in to your pricing?
Thirdly, without a per click service contract, you lose your "up-time leverage". You see, if a vendor is getting paid for each page that you print (a click charge), when your printer is down, and, not operational, they are not making any money. They need to get a service technician to you as quickly as possible to get that machine up and running and generating revenue again. You will find, that, with an independent 3rd party technician, his current work load will dictate how fast he can get you up and running again. That may be days, or, even weeks before he can get to you.
We would never think of having a digital press without a service contract. Just last year, we had a problem with an EFI Fiery Hyper RIP on one of our Versant 2100's. They ended up having to replace it to fix the problem. I saw the technician's paper work back to Xerox. That RIP cost them $75,000 to replace to get the machine back up and running. Our cost: $0.00 (because we had a service contract)