IMO, ya can get a decent (
assembled, but not bbl'd) upper receiver fer not much over $100 ... also decent BCG fer not much over $100 ... free-float handguard $50 - $100+ ... gas-block $30 - $60 ... tube $15 ... comp $30 - $100+ ... latch $20+ ... that makes a purdy nice complete upper fer around $420 - $500.
Ya can piece together a lower purdy cheap ... but it's almost impossible to do that, without upgrading the stock, grip, and/or trigger ... so, as a starting point, this is purdy good fer $270 (
add $20 'er so fer shipping and 'nother $20 fer FFL) ...
![Image](http://media.midwayusa.com/productimages/large/351/351431.jpg)
As was mentioned, ya can always swap stuff out ... the big hitters, stock, grip, and trigger, are purdy easy ... prices vary wildly. Fer the money, I'd jest piece together the upper to start with ... much bigger PITA the replace some of them things, too ... kinda nice to jest do it "right" the first time.
That's all 5.56, 'course ... .308 bein' quite a bit more.