Get yourself a nice cheap "overground" Dexter butchers knife. Most resturants use a sharpening service and when the knives get ground down/sharpened too many times the sharpening company pretty much gives them away.
I use them for butchering as well as for my bait knives. Can't say I've manned up enought to use them on a hog but WHEN the pigs reach Taxachusetts I'm gonna.
Lots of steel left on them but the blade ends up being pretty narrow. I would say $10.00 bucks at the most would get you a fine pig killing knife and you will probably buy more cause they have a ton of uses and you can get boning,buthcher,and french knives.