Used/NOS Tikka T3 30-06 $500
Black Friday 3-9x42 MQ $450
30mm DNZ $65
Sig Kilo $400

I could really cut the rifle price in half with a used $250 Savage 111 or Marlin XL7.

I think I could get to the point of ranging comfortably with my reticle to about 600 yards. Past that I think things would get tricky without a pretty high confidence value for the size of the target. I calculate target sizes with my reticle regularly with known distances. Same equation but there is going to be more error when your estimated taret size is an input. With enough experience I'm sure things could be stretched out more but I doubt that many shooters can range a game animal (with reticle) at over 800 yards accurately enough to be confident of a first round hit in the vitals.