I'm doing the same thing for the inlaws this year. Artscow.com has them for 9.99 each. I've never used them so I don't know how they will come out though. Right now shutterfly has a special where I think it's 18.99 for the first and 13.99 for each one after and I believe you get free shipping. I may look into doing it at the store this week and see what their prices are.
I use Shutterfly bc/ that's where I keep my pictures. They are easy to do, and not very expensive even at full price (although I have no idea how they compare to anywhere else), but they often have sales/specials/promotions, so if you google, you will likely find a code, too. They have fast shipping and the finished product always looks very nice.
I made one at walmart.com last year (16.99 plus shipping), but am doing one on shutterfly this year (19.99 with no shipping). The background styles & number of pics per page is better/more at shutterfly than walmart.
Re: cheapest place/way to make calendars?