Re: 10/22 where is the best place for receivers?
I've gone both routes (bare rec. and donor rifle). IMO it really depends on how much you want to spend.
One of my best shooting 10/22's started out as a std. I swapped the barrel, stock, and trigger out. Selling off the parts helped offset the cost of the upgrades.
My Tac. Sol. bbl rifle started as a NIB bare receiver. I can't remember right off hand where I got it but will try to find the emails when I get home. When I got finished it was a new rifle but cost considerably more to assemble than the other.
I'm waiting on my Form 4 for a SBR'd Zimmerman so haven't shot it yet... but have gotten to visit with it at my dealers and the fit/finish is top notch.
For the price of most bare, NIB, factory receivers you should be able to find a used rifle. For the price of an aftermarket rec. you could probably find a rifle and a half... maybe even two.