Your and my response will be the only ones here in "GATE", if you want to hear about others learning curves you should post in the black rifle area.
GATE is for one person to ask a question and only the GATE moderators can reply, most moderators don't cross topics. Only Armalite makes AR10s, other companies make 308 ARs. There is no mil spec 308 AR so they are all different, most do not mix and match like AR15s do.
$1600 limits you to DPMS, RRA, Bushmaster and Remington, since DPMS is really the only company that sells parts I would say start there. If you are talking about pinning an upper and lower together then RRA sells uppers.
If you want a real AR10 then Armalite is the only place to get them.