I have to admit, thats a really good deal if they will take a used Kayak back if you're unhappy with it. Nice! give us a report when you get it out. BTW If you are ever interested in a kayak fishing...
The best advice I can give is to never buy a kayak until you've been in it on the water. it's too much of an investment to get one that you won't like once you get it on the water.
