Where to get cheap longboards?

ive been skateboarding for like 2 years and all i can do is ollie. so ive decided to maybe try longboarding. mostly cuz its more of a riding sport than skateboarding. wheres a cheap place to get a longboard. i mean like 20 or 30 dollars if possible. i dont want to get it online like ebay or somethin. does someplace like walmart have any, or some other common store in about every city.