You can buy the plastic grips at AIM Surplus.
The only U.S made wood grips I am aware of are at Ironwood Designs.
Be careful when swapping furniture on AKs. To legally have features like high capacity magazines, pistol grips, folding stocks, bayonete lugs, or flashiders they have to contain a minimum number of U.S made parts. Most importers use the cheap U.S made black plastic grip towards that required number. If you put on an imported grip from Russia, Romania, Poland, ect you may be breaking the law by doing so.