The purpose of Patreon is to allow people to support your work because they want to support it. So think less in terms of value for subscribing, and more in terms of thanking people for their support. NPR does it right with cool "thank you" gifts—shirts, mugs, etc.—items that have little general value, but feel special to persons who donate.
I would not recommend implementing rewards which fracture you player base by making non-Patreon customers feel like they're getting a second-class version of the game. CMON is infamous for this type of reward—to the point that it feels almost pointless to buy their products unless you were a kickstarter backer because the game is missing major portions.