You say you want a WW11 M1 Garand that is in nice shape and "mostly original". You also ask is it better to get a "rebuilt one" or an "original unmolested".
Without a doubt an "original unmolested" would be number 1. The problem is it will not be that easy to find, and when found, the price will be quite high. $ 2500.00 plus
2nd choice would be a nice correct RESTORED WW11 rifle. $ 1500. + or - depending on factors such as year of manufacture, condition of rifle and wood.
A rebuild, meaning a rifle as rebuilt post war by a U.S. Arsenal, $ 700 plus depending on condition and wood.
I don't think you will find these types of rifles at CMP. For what you seem to want you might consider The "Garand Marketplace" of the Garand Collectors Journal. Don't get me wrong, CMP is fine if you want a shooter or a nice Post War rifle but not for what you seem to be looking for. You can also find nice rifles at auction, even on G.B., but you really have to do your homework if buying from an auction.
One other thing, if you are considering buying a "mixmaster" and restoring it yourself, don't, unless you just want the fun of doing it. Money wise it's much better buying a rifle that someone else has correctly restored.