Even if you toss a pre-certified module into your product, it will most likely still need FCC
cert before you can sell it. Contact one of the certified test labs if you aren't 100% sure.

These guys are one of the best http://www.celectronics.com/

The finished product (even if it uses a pre-certified module), may still need final certification
of the finished product before you can legally sell it.

An FCC certified test facility will tell you straight-up if your product needs further FCC cert.

They will tell you without charging you for the info, and it's worth the effort.