I've applied at Costco many times and never heard anything back. Think I was always looking too qualified. I don't know if they pay $20/hr though, if they do, I'd probably look into that for part time work in the winters if I needed to.
You shouldn't assume that a college degree will saddle you with a lot of debt. CU Denver is something like $3,000 a year (or it was when I went), and you could easily swing that while working at Costco.