I meant simple formula as in cost times x%. I have pricing tiers. A wholesale cost, a direct from me price, and a gallery price which is my direct price plus gallery commission (which is usually 50%).
Printers really depend on what you are print. If you are just making regular photographic prints Costco does a good job and are very price competitive. Camera Canada has both a regular print lab and a pro lab with a few more print options than Costco. If you are wanting giclee prints I'd highly recommend Derek Copper at Reproducing Art
http://www.reproducingart.ca/printing/. There are lots of other places to have printing done though.
When I first started selling prints I invested quite a bit of time and money looking for printers and testing their quality. I suggest anyone interested in making a career of it does the same thing, and do your own rereplacement. What worked for me might not for you; or you might find someone doing as good of job for a better price, or someone more local to you that you can work with face to face (always a great option!), etc.
The internet is a great resource and a google replacement will usually turn up loads of places to investigate.
Cheers,
Roberta