Here's a link to the B.C's of various Sierra bullets.
http://www.sierrabullets.com/documents/BallisticCoefficient-rifle.pdf
I was easily able to hit a 22" round gong at 800 yards with mild charges handloaded on 7mm08. 120grain spitzers over 42-44 grains Varget (depending on temperature) Not even using a boat tailed bullet. Since I picked my bullet for much shorter hunting ranges, you could do a LOT better than mine -- B.C. in the low .300's. And I had a realtively short barrel -- 22", bull barrel chosen to reduce barrel whip. I chose 7mm08 over .308 to get higher BC and higher velocity with reduced recoil. Reload cost is probably 40 cents per shot.
If I were willing to abuse the brass at bit more, I think I could get to 1000 without too much trouble!
If you REALLY want to get into it, I think you can get a B.C. in the .60's with surplus 50BMG FMJ's for 85 cents each. Wideners has cheapo powder at $8/lb. Once fired brass is well under $1. There are single shot 50's out there at reasonable prices. If you are willing to pay $2/bullet, the Hornady has a BC > 1
For my money, I'll stick with the 7mm08!! Velocity is a huge friend at long distances, so I'd go with a 140grain boat tail, punish the brass a bit to get a bit more velocity and I bet I'dd ring that gong on every single shot......