That is a super cool idea. I've seen it done, but not with coins. The youthpastor at church did one for his daughter of her first year on his Mac with a program it came with.. iPhoto or something like that.
Another on-demand publisher is www.lulu.com That's where I have been planning to have the printing for the second edition of the slabbook whenever I finally get it finished. It looks like I can get a 500 page casewrapped hardbound printed for not much more than it was costing me to do the 436 page comb bound First Edition