I bought a 6'x6' piece of marine carpet from Lowes, cut it, and installed snaps for < $45... It looks great and I don't worry about stains!

Thats a great idea!
Just make a template, cut the carpet and install snaps. Then bring it to a local canopy/marine upholstery shop and have the edges bound. I can't see spending more than $100 total.

These ideas are getting better and better.

Thanks zdek & mtgbiker.

I looked into binding the edges and here's the deal... If you get the edges bound, the material that they will use is NOT UV resistant and will deteriorate like within a year (the binding place told me). Another (better) option is to get the edges whipped - they wind thread around and around the edge... I looked into both - my local people wanted between $4 (binding) and $10 (whipped) per foot. That would mean the whole perimeter and the slits for the seats... that's a lot! I'm young and know there will be mishaps on the boat, plus the Lowes carpet seems to have a very good backing - for <$50 TOTAL!!!