They sell it but the resin is almost always out of date... its best to order it so its fresh or get it from a marine repair shop.

 

will this fiberglass box sound as good as a wood box? heavier or lighter? any other +/- s

 

It will depend on how you build the box. A fiberglass box will be lighter. They each have a different sound to them but they both can sound great. You could always make a wood bottom and a fiberglass top.

 

I've always had good luck with Mertons http://www.mertons.com/ Stay away from local retailers the stuff they sell sits on the shelf too long and tends to give bad results. If you need to try local try an autobody supply shop, or bite the bullet and pay the extra that West Marine charges. Don't forget that you can buy thickeners/Fillers for Fiberglass such as THIXOTROPIC POWDER. It will help when you are trying to mold something in a vertical position.