For close range - Scorpion EVO in 9mm
For mid range - AR-15 in .223 or 7.62x39
For distance - Barrett .50 BMG
50 bmg rounds cost $3.50 -$5.50 EACH
338 Lapua are almost the same.
300 Win mags/ 7mm mags 1000-1500 yds. depending on the load. $1.00 -$1.50 per round, unless hand loading.
Barrett 50 bmg costs $3500-$7500 depending on model. Remington 700 in 300 win mag or 7mm mag, $750-$1000.
50 bmg is one HEAVY gun.
23-33 pounds, sans scope and ammo.
About 4 oz per round. 100 rounds = 25 pounds
Add on optics.
Going to be expensive for those handling the punch that a 50 or 338 gives and the ranges they reach.
Lastly...the gun is only as good as the shooter.
Whether the gun can reach out 1000-2500 yds, doesn't mean the shooter can.
Most people will never go beyond 400 yds or even 600 out west.
600 yds is someone experienced.
Unless someone is experienced and very good with a gun, a gun in 308/30.06 is more than adequate, and the rounds are cheap, especially when hand loading.