I just bought one for a rifle. I believe it was $3500.
I think I would get a three hundred fifty dollar one and fabricate my own mount. Or, get with a machinist and fabricate a high pressure fifty caliber air gun and attatch it to that.
Then with servos you could harvest them on frozen winter nights with the cold to preserve the meat (although I guess you would still need to get out there and bleed them).
No pigs equals big gardens that are impractical with the current swine infestation.