RWC is Road Worthy Certificate and club reg is a vehicle registration which gives you a substantially reduced government vehicle registration fee provided your vehicle is more than 25 years old and you are a member of a club and use the bike for only a restricted number of days a year.
E-Bay is not always the best source for parts. I'd ask the local biking community where you are at, as to where to buy parts and accessories. Mirrors aren't that expensive, a good shop can fit you with an aftermarket one of reasonable quality that will fit your mirror mounting socket and provide you with good back visibility, enough to pass inspection. Also, the original may be available too, inquire at a dealer. Some dealers also sell aftermarket parts too through special order.