Air guns have come a very long way. Some of the bigger custom ones are capable of taking down a Bison (full passthrough, 50 caliber).
A fully tricked out PCP rifle will run you north of $3k (rifle, scope, tanks, compressor). Check out the countless youtube videos of guys taking out pigeons and doves at 200 yards and hitting targets at 300+ yards. Calibers are anywhere from .177, .22, .25, .30, .35, .45, .50.
Regular 'springer' rifles are amazingly accurate and powerful too. The Diana Air King 54 is accurate out to 130+ yards.