http://www.bing.com/shopping/ar-15-mod4sa-lower-receiver-stripped-mod4sa-ar-15-lower-receiver/p/7EE5D182FE1A5F355003?q=ar+lower&lpq=ar%20lower&FORM=HURE
Ok, you're at $90 for a stripped lower. Keep going until you hit $500.
You need:
A lower receiver parts kit (including trigger, hammer, sear, trigger guard, pistol grip, and all the little pins and springs,) $80
A stripped upper (with forward assist plunger and dust cover. So much for saving money the MP15 Sport way...) $100
A bolt and carrier, $110
A barrel with gas block and sight, $145
I'm already over $500 and I still need a charging handle, gas tube, buffer and buffer tube, buttstock, handguard and delta rings, rear sights, etc. Not to mention an Armor's tool or a castle nut wrench and a barrel wrench.
You get the idea. Even if you were a very shrewd internet shopper, it's still more like at least $650 these days to piece together a carbine from new parts, and even more by the time you add in all of the shipping charges from the various web sites.
I'm sure you have a well stocked parts bin, so a lot of the little stuff you already have on hand. I bet you could pull off a $500 build from all new major parts plus your scrounge bin. But for a first time AR owner, this MP15 Sport isn't a half bad deal.
It's worth taking advantage of deals that aren't "half bad." Five or six years ago, ArmaLite had an introductory deal on their Eagle Arms polymer (manufactured by Cav Arms) lower receivers: $125, including a matching lower parts kit. Not too long after that, I got an ArmaLite SOF upper assembly (16" chrome lined barrel, mid-length gas system, etc.), complete with bolt/carrier and charging handle, for $379 on clearance. Total price for the carbine: $504 (plus FFL & shipping, of course) - not "half bad!" It's worth watching the ArmaLite website for sales & clearance items.
ArmaLite (http://www.armalite.com, "12 Days of Armalite" sale) currently has a complete 16" upper assembly, including bolt carrier group & charging handle, on sale for $399 - almost $200 off the list price. If you can find a deal on a lower w/ parts kit (or have some of what you need in your parts box), you could probably come in under $600.
Merry Christmas!
And don’t forget tools: upper receiver holding fixture or barrel clamps, barrel nut wrench, assorted punches, and 100 ft-lb torque wrench to name a couple. Unless you already have these tools or can borrow them, there’s about another $100 worth there. Just buy the assembled gun if you’re new the the AR15. I’ve put together two and I like the idea of being able to service and modify my own ARs.
And don’t forget tools: upper receiver holding fixture or barrel clamps, barrel nut wrench, assorted punches, and 100 ft-lb torque wrench to name a couple. Unless you already have these tools or can borrow them, there’s about another $100 worth there. Just buy the assembled gun if you’re new the the AR15. I’ve put together two and I like the idea of being able to service and modify my own ARs.