I have purchased parts from D&R, Classic Industries, Rick's 1st Gen, The Paddock's, Year One, from Jim Subbings at Heartbeat City, plus a number of parts and services found in Hemmings Motor New publication. I prefer the more consistent quality on repro parts from Risk's 1st Gen, and have not had any problems with their service. I have experienced different levels of knowledge from the service techs at Rick's.
Risk's sells interior door panels made by Al Knoch Interiors who is well known for top quality reproductions for Corvettes. My 69 deluxe interior panels are from Rick's 1st Gen are very nice pieced made by Al Knoch. World Wide Camaro Club members get free shipping from Risk's which helps off-set some costs. I have bargained and received lower prices from vendors by comparison shopping.
Good luck with your project.