If you get this dialed in, you could charge a LOT more. Your big market is enterprise customers that need to review schematics that are 30 pages long with FPGAs, memory busses, and lots of connectors. You should segment the hobbyist for the $10-20/month and then enterprise customers at $+100/month. If your product catches just one major problem in a schematic, it could save a full revision which is worth thousands of dollars.