Not being snarky, I'm more curious, then what do you define as milspec? I know pretty much if its not made by Colt or FN some people will say it can't be milspec.
Well I wouldn't listen to those "some people", lots of manufacturers make very good rifles that meet or exceed the mil spec.
Common examples of places where some manufacturers save money:
Carbine weight buffer instead of H buffer
6061 aluminum on RE (vs 7075)
Bolt not shot peened C158, or not HPT/MPI
Barrel not even a 1:7 twist
There are rifles that exceed the spec, rifles that 'meet' the spec, rifles that are very arguably 'as good as' even though they are different, and rifles that simply cut corners to save money...of the ones that cut corners some will work just as well for the end user as a 'to spec rifle', some may not.
For example, having a 6061 receiver extension that is mil-spec diameter probably won't be something you ever notice. I'd rather have the 7075 with cold rolled (not cut) threads because it is stronger and it is better, but there's no rash of RE failures because of the 6000 series aluminum.
And you can probably use a C weight buffer and not notice, but long story short I and others would rather have the properly gassed carbine with the H buffer, especially as the round count starts to climb.
You simply have to watch the sales:
Lower build kit:
http://palmettostatearmory.com/index.php/catalog/product/view/id/10301/
The BCG isnt currently on as good a sale as when I purchased it (July 4th sale)
http://palmettostatearmory.com/index.php/catalog/product/view/id/2321/category/2203/
You can eat your hat now
$110 =/= $59, you can eat your hat now.
I also guarantee that is a carbine weight buffer, not an H, you may eat your backup hat now.
Now, if you want to argue that those parts, which are still over $600 (this isn't July 4th), are "as good as" mil spec or "you won't notice the difference", you are more than welcome.
But the bottom line is that those parts are not to the 'mil spec' standard, which is to be expected for $600, which is why I said that I don't think you can build a 'mil spec' rifle for $600 new.