Ghia specific stuff
KGPR http://www.karmannghia.com/
HOG http://www.house-of-ghia.com/
other than that
Aircooled.net only stocks good stuff, has a great tech section, and John is very forthcoming with information.
http://www.aircooled.net/
CB Performance is known quality http://www.cbperformance.com/
CIP1 carries many many brands, both good and bad. DO YOUR HOMEWORK http://www2.cip1.com/
Empi is very suspect