I have long been an advocate of running proxy tournaments of eternal formats to get players interested. The logic is that when they realize they like the format they will get into it and buy cards. It's also a way for a store to attract people who play that format to the area. It's also a way to break the monotony of playing standard all the time. I think a 10/10/10 structure works well for Legacy ($10 entry, 10 free proxies, $0.10 per proxy beyond the first 10) and an "up-to-75 proxies" format favors Vintage. Vintage players actually don't mind playing against people with proxies in my experience, because it allowed them to play Vintage, and it allowed players who are interested in the format to see how cool their sweet foily decks are. A pimped Vintage deck is as much about being seen as it is having, and people with no exposure to the format are totally unjaded and very impressed with a pimped deck. Maybe it was just the people I played with, but they were totally cool with proxies and had a blast even when they lost to me playing a swamp with "Genesis Chamber" written on the back in Sharpie.
I found an LGS posting on Reddit about their experiences with a proxy eternal tournament - in this case it was Legacy. Not only did everything turn out better than expected for the store, the comments section on reddit was less filled with diaper-pooping than I would have imagined.
Has your store ever taken this advice and run a Legacy event? This store did $1 per proxy - what we your store's policy? How did it go? Would you do it again? Do none of these followup questions make sense because you answered "no" to the first question? Leave it in the comments.