Free: Contests & Raffles.
FWIW John Barsness, a credible gun writer (to me) wrote that he did extensive testing and found no ballistic advantage to cleaning brass, so he doesn't anymore. (Not an exact quote but my paraphrase combining several places he has mentioned this.) If I recall correctly, he did find that some carbon left inside the case neck eliminated or greatly postponed cold welding (?) of bullet to case in ammunition unfired or stored for a long time. I'm not sure of the correct term but have found long stored ammunition to have some bullets adhere quite strongly to case.I like the look of clean brass but have backed off of cleaning more than wiping the outside.