The hard part in this business is handling successfully both printing and software development parts. If you offload any of the tasks to 3rd party you can't offer cheaper option than competition anymore. If you do both then you have more problems. I don't know everything about competition but let's have some fun:
* Snapfish - completely focused to West Countries (North America and West Europe). They will never be able to conquer other markets with current technology stack/solutions they have now. They can solve the problems they have but I'm not sure how capable they are to do that.
* Google - yes, Google, is in this market as well. They have small simple solution but I think they have offloaded printing to 3rd party and printing books in their side is very expensive. I think Google will never be big player in this market but photo books will never get more expensive than Google's offering.
* Canva - you can create photo books using canva as well. They have quite amazing (while not pixel perfect) software stack but they don't offer photo book printing. You can download PDF and print it in local print shop if you want to get it cheaper.
I don't know what's local situation in USA but if you are in Europe you might consider printing somewhere in East Europe - most probably you will get lower price and good quality.
I use Walgreen's with local pickup for prints.