Check out the UCI Website for all the required safety equipment.

Basic Rundown of it:

Full Face Helmet (DOT not required)
Gloves
BMX Pants
Jersey/ Long sleeve
Closed toe shoes
Additional equipment - neck braces, chest protectors, elbow pads, etc.

Used – Alberta BMX buy and sell group on Facebook, VarageSale, FB Marketplace, Kijiji, other members/clubs.

New –bike/motorsport shops – B&P Cycle, Jack Carter Powersports, NorthStar Bicycle, Bow Cycle, and also a variety of online sites