as stated above Schuyler arms has a great deal on Aero parts right now.
http://www.schuylerarmsco.com/catalog.php?category=113338
search their site lots of good deals on Aero stuff. that's where I got most of my parts for my 308 win AR10 build. also, check out tomstactcal their nitride BCG is very nice at a good price point. and joeboboutfitters has a great deal on hipertouch triggers right now. and check out manventureoutpost for stocks and grips and handguards.
and for how to help or what is compatible with the AR10 platform this site helped me a lot:
https://308ar.com/assemble-308-lower/
here is my build and it came in at about $1850.00 total with the optic + misc. parts like gas tube etc.
Aero upper assembled (dust cover FA) $155.00
Aero lower $110.00
Aero lpk $65.00
toms tactical nitrided BCG $139.95 free ship.
Aero buffer tube and spring and buffer $49.00
sprinco orange spring $8.95
KAK industries heavy buffer 5.3 oz. $55.00
SLR adjustable gas block $110.00
hogue grip and stock $42.96
UTG pro series key mod handguard (high profile) $133.78
hipertouch 24E trigger $129.95
Mega arms 20'' nitrided stainless barrel (on clearance $200.00) they got bought out by Zev technologies.
VG6 brake $40.00
magpul genII backups $69.41
Meopta Meostar 4-16x44 mil-dot scope (ebay $450.00)
leupold mount $89.00