Two common plastic options are ATI and Ram-Line. The ATI has a monte-carlo style buttstock, the Ram-Line doesn't. They typically retail for approx $80 new. Both are advertised as no-gunsmithing, d.i.y. drop in fit. With both brands there are people who report from their own experience that it is true and others who had trouble and needed varying levels of work.
I have one only because it came already fitted to a rifle I wanted for other reasons. And it was advertised as needing some final fitting. It turned out to be defective - the forestock is bent downwards slightly in front of the action so it never comes up to the barrel as it should. It's an ATI, but if I were getting another, I'd choose an ATI because of the monte carlo stock. But I'd check it very carefully right away so I could take it back if defective.