That seems to be the going rate these days. Private sales are about it for these, Tapco quit selling them a long time ago. They went for like $17 back then, sometimes on sale for less than $10.
Before you invest in one do some research on the machining required to finish them. For a blowback build they wouldn't be too bad, but getting them properly heat treated to withstand a .308 build looks to be difficult. There is also a major lack of accurate blueprints to work from.