omg....
Walmart..... REALLY?
REALLY?
Shame on anyone who thinks WALMART does a good job.
Often, the lab tech's there don't care to turn off auto correction on their printers, and if you ask them not to correct, they'll most likely ignore it, because what do they care, it's not like they're hurting for business. So something that looks correct on your monitor, will look f***ed up in the print as a result because there's so many orders, they can't take the time to make sure the results are there.
Usually camera stores, and the more pro-oriented the better, will easily surpass the quality of walmart.
I work at a Ritz right next to a Target, and we get people all the time who get pictures printed at target, and then swing by us asking if it looks right. We reprint it without the auto correction, and the difference is night and day. Not only in color accuracy, but in acuity as well, because the Fuji's or Noritsu's that Target use, do too much sharpening, and it ruins pictures.
Also, investigate on what printers the local stores use for enlargements. We use Epson 7800's with their premium 5 star papers for anything larger then 8x12. That's archival, damn near fine art quality. You can't beat that in a 1 hour joint.
Even on the 4x6's, the difference is ridiculous.