Unfortunately a cheap longboard wont work, even a 10 footer. Suping is huge around here on the gulf. I went a couple times last summer, and it was amazing. I have tried Suping with my Friends 11 foot foam long board, then my local shops sup, and the difference is ridiculous. There are some guys that sup down a river we have here, and they look like there having a good time.
local shop that has a pretty sick deal on a yancy spencer (look in the advertised square to the left)