Looking at the Sequentia website, I see that they also have a panel that looks like tile, so maybe that is what you were looking at, but $10 per sheet would be real cheep for FRP.
Here is a web site for Sequentia brand FRP http://www.kemlite.com/structoglas/str_products.cfm
I can't really find anywhere that they mention UV ratings. There is a place where you can ask a question though.
Here's their page about Filon, which is designed for RV use:
http://www.kemlite.com/filon_frp/filon_frp_index.cfm
although I don't know if they would sell small amounts, or would only sell to manufacturers.
