I don't know - I think the OP did ok with his parts list. This is what I've gathered up for my Standard 20" A2 Rifle Build:
CDNN
DPMS A2 Upper Receiver & Standard A2 Flash Suppressor - $55 (shipped)
Aim Surplus
Anderson Arms Stripped Lower Receiver - $40 ($65 After $10 Shipping & $15 Transfer Fee)
PSA
A2 Delta Ring Assembly - $22 (shipped)
Delton Inc.
Complete CMMG M16 Bolt-Carrier Assembly - $105 (shipped)
Brownells
DPMS A2 Upper Parts kit w/Charging Handle - ($50)
DPMS Lower Parts kit - ($50)
Standard Rifle Gas Tube & Pin ($8)
M16 Buttstock cleaning kit w/case & oil bottle - ($15)
Total price (w/ free shipping) for everything from Brownells - $123
Windham Weaponry
A2 Gov't Profile 1in7 twist 20" A2 Barrel Sub-Assembly w/standard A2 front sight base & sight assembly, handguard end cap, sling swivel, rivet, & barrel nut - $240 (shipped)
E-bay
5 A2 flash suppressor peel-washers - $5 (shipped)
AR-15 Equipment Exchange
Standard A2 Rifle Stock Assembly (new in wrap w/metal trapdoor) - $60 (Shipped)
KnifeCenter.com
Standard OKC M9 Bayonet - $65 (shipped)
Local Gun Show Purchases
Standard A2 Black "Silent" Sling Assembly (new in wrap) - $5
2 Center Industries Corp 30-round mags (new in wrap) - $25
Standard set of A2 hand guards (new in wrap) - $10
So for this brand new basic AR15A2 rifle w/ bayonet, sling, trap-door cleaning kit, & two 30-round mags, it has cost me a grand total of $780. Could I have saved a few more bucks?...sure, though for me, the extra costs spent to ensure having all new parts without a bunch of haggling, uncertainty, or unnecessary waiting was well-worth it.
For now, I am leaving this rifle as a completely unassembled collection of component parts & supplies packed away carefully in a simple, cardboard box as a kind of tribute to the olden WWII days of "Jeeps-in-a-crate" with this being my "Rifle-in-a-box" version of that practice, though I will, at some point in the future, assemble it; QA & test it; and of course - post pics of it both here & in it's own thread on these forums later on.
I look forward to seeing pics of the OP's build as well. There's something about assembling your own rifle; firing it; and hitting your target - that just makes you feel instantly better about being you.
ETA: My AR15A2 "Rifle-In-A-Box"
ETA:
Couldn't resist the urge to put the thing together:
Just ordered a couple more of these receivers to finish up some other projects...
FlDiveCop71