Oh, absolutely true. The entry requirement for joining the 501st is having your own full canonically correct costume, and preferably full white armor. Up until fairly recently that armor wasn't licensed for sale, so it became a point of pride for those guys to build their own to a very high standard; there are very few members who don't have some experience with casting Star Wars armor. (However, according to the Legion's rules they are not supposed to mfr. the armor for the purpose of sale.)