The biggest hurdle in a kit build for the M14-type is the parts. The parts market has dried up. The last time full kits were available was a few years ago and they cost about $700 at the time. You'd have a heck of a time finding one floating around, though I'm sure there are some out there, but I don't want to think what you'd have to pay for one. If you've seen parts kits, where'd you see them? There's plenty of people looking for a good set at a decent price.
You could find the parts here and there, but that's alot of running around, searching, and in the end will cost a good deal more.
Anyway, let's say you get a receiver for $175, and a parts kit for $700. That's $875. You'll need a gunsmith, or you can do it yourself with about $100 worth of tools, depending on what you already have, but you'll definately need a couple of special tools. Either way you're looking at another $100 by the time you're done. That gives you $975, not adding in the shipping and what not. So it's safe to say you can round it up to an even $1000 as an estimate.
A fully assembled SA, inc. will cost about that, so I don't believe that it's cost effective to do it yourself. You can find non-SA, inc. guns for less than what it would cost for you to build one. A fully assembled SA, inc. gun will also give you a lifetime warranty.
If you want a specific version, or you're buildign a match gun, then it could be worth it, since buying a whole gun and all the extra parts gets even more expensive, but unless you really need a gun built, it's cheaper to just buy one built.
Now that being said, I built a TRW kit on a Polytech receiver because I wanted all USGI parts on a forged receiver. I could have bought a SA, inc. for less, but I wouldn't have had the exact gun I wanted.
In the end, the lack/price of kits makes buying whole a better path to take.
Ross