Three, or four, adult mice is overkill.
A Cornsnake only needs ~one~ appropriately sized feed item per feeding.
An appropriate sized feed item is at least the same girth (minimum), as the widest portion of the snake's girth, and up to 1.5 times (maximum) the widest portion of the snake's girth.
See here what I wrote for feeding times of an adult Corn:
http://www.faunaclassifieds.com/foru...d.php?t=305710
Whether the feed item is black, white, grey, brown, gold, spotted, etc., or hairless, makes no difference.
Although, with the hairless, I imagine digestion may be slightly easier (though, typically, unnecessary) ... &/or maybe handling is better for people who are allergic to mice.
Many pet stores carry frozen mice but the price is, comparatively, high.
A cheaper route is to purchase mice from companies/breeders that supply them. Only thing is that they sell in bulk (i.e. each bag can have a 25, 50, 100 count).
There are plenty of companies to choose from. Although there are more, here are just a few that I have had good/okay experience with:
http://www.americanrodent.com/welcome.html
https://micedirect.com/
http://www.rodentpro.com/
You can also check for local suppliers/breeders.