as with many things in life, quantity reflects pricing.
our 8x10's are 8.95. Before some folks gasp and go "wtf", that is the price for the average guy wanting a print. Our wedding photogs that bring in lots of clients and prints obviously don't pay that price. It all depends on volume and history.
Same with most places, however with the big online labs...you'd have to really be a regular and have huge volumes before they cut their prices anymore than they are.
Like said above, your pricing depicts your profit. Even if you bought at 8.95 you can make money selling your product correctly. Obviously 8.95 is high, but it's an example.
I have bought from WHCC, MPIX, costco, and walmart, and our lab in house.
as far as cost, they are all varied. Quality, forget walmart, some like costco...me personally...not so much. Mpix and whcc produce a fine product. We print at the same level as the latter two. Our metallics I believe and others attest locally, that they even rival whcc and mpix both. Some photogs use us just for metallics and the online guys for the rest of their needs, for cost purposes alone..as the quality is equal otherwise.
Shop around locally and don't rule out local labs. You may find someone like us who does a damn good job, but is just overshadowed by the larger online guys. You can build a personal rapport and get great deals and great service.
on another note, anyone seen that new (new to me) metallic looking canvas print? We got samples in yesterday...they look pretty sweet. We should have some here soon I believe, I want to see those things in action.