Getting rid of schematics sounds like a bad idea. I do not see how you can have market for items when you can flood them so easy with no schematics. As a solo player i have a factory with a very rough estimate of 5-10 billion in schematics without using any exploits.
I think you could do some alternative ways to craft things. For example, you could add in lesser schematics that cost much less but use 3-4 times more mats to craft their item. This would keep normal schematics the only to profit off the market but would pretty much cap the profits people can make to 3-4 times the ore cost.