Do you enjoy printing? How much time/effort does it take to go to Walmart (or wherever)? Do you want snapshot prints that will be replaced in a few months/years or something to be framed and kept?
Per print will be cheaper going to Walmart. The quality is going to be fine. You won't get exactly what you want, because you're letting someone else do it, but if it's close enough then it's good enough. If you like printing and aren't doing a huge amount and want to get it just the way you like it when you want it, then do it at home even if it costs a little more per print.