Just for whatever it's worth, I used to print 8x10s occasionally at Walmart and had good, consistent results. I used their "instant" print service (don't recall what they actually call it) where you insert your media, select what you want printed, and the prints come out in just a few minutes, not their drop-off service. The local Walmart has some kind of HP equipment for this. I haven't used them for the past year or more since I started ordering from Mpix. As they say, YMMV.
Another issue: You wrote about printing your edited photos, but then mentioned taking in your SD card, which would contain your original RAW files I assume, not your edited images. You will want to send JPGs in sRGB color space to whatever print service you plan to use. (Just as an experiment one day I found that the HP devices at Walmart could also handle 8-bit TIFFs, but seemed to choke on 16-bit TIFFs.)