Don't be cheap on a SHTF rifle. Afterall, Shit Hit The Fan, so you don't want something jamming on you. An FAL style rifle will be not much cheaper than the M1A/M14 style rifle, but the PTR91/H&K91 is a tried and tested platform aswell.
I enjoy all my S&W M&P15's and spent $1K a piece on them. Personally a good investment into something I will most likely utilize if necessary. The peasant rifle (AK47) you speak of is a great investment. I will agree that it is a successful, reliable, and simple weapon that is utilized by many countries. It's tried and tested, not to mention a prefered weapon of 90% of our enemies. If you want a GOOD AK47 variant style rifle, look into Arsenal's AK47's. They're made in the Las Vegas area, and as far as accuracy is considered, it should top most of the Soviet era firearms.
I guess it's all in what you want, but personally, you go cheap and you WILL get cheap. It's as simple as that. You've got to pay, to play in the gun world. And personally, I'll depend my life on something I may have to spend a little money on. I don't put a price on my life or safety, just to save a few hundred.