is it really cheaper to buy ink and print digital photos at home or at the store

I've wondered the same thing. But we must also figure out the wear and tear on our printers, too.

I think a lot depends on how you print them, too.  I often copy pictures into a word document and crop them in word.  I have picture paper this is 8 1/5 x 11 so if I need a bunch of smaller pictures, I can print out a bunch on 1 sheet of standard sized picture paper rather than printing 5 or 6 pictures on 4x6 printer paper and cutting away what I don't need.

When walgreens has a sale or offers a coupon where printing is 5 cents a pic, I'll often do that if I need a whole bunch.  I mean for a $1 I can get 20 pictures and I can do the whole process online -- except for picking them up.  Not really a bad deal when you think about it.  If you are able to wait for pictures for whenever they offer this deal in printing, set up a file folder in your computer labeled "pictures to print" or something like that.  Each time you take a picture that you know you'll want put a copy into that file; at least for me, this makes it easier to find them when it's time to upload them online.