This should get you started. :eyepop:
(All the following company names are links to their store sites)
Excelsior Rocketry - custom nosecones and decals, incredible scale models
Aerospace Specialty Products - wide variety of scale kits, building supplies 0.16 precut fiberglass fins, parachutes
Qualified Competition Rockets - very competitive kits for virtually every NAR event, pistons
Fliskits - Rose-A-Roc and MMX competition models
Apogee Components - Medalist motors, vacuform nosecones, lots of other parts (incredible amounts of free, very useful competition advice)
Kevlar Store - great prices on very high quality braided kevlar
Pratt Hobbies - vacuform nosecones, particularly egglofter cones, launching supplies
Balsa Machining Service - parts, parts, parts, but particularly custom rings, laser cut fins, etc.
Semroc - parts, parts, parts, but particularly laser cut fins
Venus Rocketry - not currently operating because of illness but truly incredible FAI kits and supplies, get well soon, Mark!
Totally Tubular, now part of eRockets - great part supplier including a number of very hard to find parts not carried by anyone else
ACP Composites - fiberglass fabric, etc
True Modeler's Rocket Kits - great scale models