Vendor (location) -- Specialty

Pineapple Racing (Portland, OR) -- Engine building for racing and street performance
Rotary Performance (Garland, TX) -- Tuner, products for all RX-7s
Mazdatrix (Signal Hill, CA) -- Stock and performance parts for all RX-7s
Racing Beat (Anaheim, CA) -- Major tuner/vendor with ties to Mazda
Pettit Racing (Ft. Lauderdale, FL) -- 3rd Gen performance products
M2 Performance (Concord, CA) -- 3rd Gen performance products
RotaMax (Arlington , OH) -- Commerical rotary engine products

Great Vendor Links site (with rating/feedback system):

Northstar Rotary Rockets Club: Vendor Links