With the Evan McCulloch Mirror Master (whose name escapes me) I can see that being reasonable. He was a hired mercenary (in Animal Man) before he joined the Rogues proper, and I can see he might be wanting to be sure that he's as far ahead of the game as he can manage, so is always buying/stealing new "toys" as he doesn't have Sam Scudder's bizarre aptitude for insane optics and on his first few missions at least wasn't sure how some of his mirror weapons worked.