Mid-length RRA from ADCO turned down under the handguards. Might be up over $500 a bit though.
Here's what I put together (I'll be using it for coyote hunting too, coinidentally)
Sabre Defence Gov't profile, mid-length, chrome-lined, 1/7 twist barrel- $285 shipped- Talon Arms
CMT M4 cut upper- $99- Bravo Company
CMT Bolt/Carrier/ Charging handle- $140 (can be found much cheaper as a package)- Bravo Company
RRA OD Hand guards- $23.50- ADCO
ARMS #40 BUIS- $100 shipped- ADCO
Just a little under $650. This upper could be put together for under $500 If you could skip the hand guards, BUIS, and find a better deal on the B/C/CH. An aluminum FF tube is pretty cheap too. I don't know if Talon Arms could swap a railed gas block on there or not, though.
Hope this helps a little.
WIZZO