Bought my son the Mossberg in .270 for $199 at Academy Sports. Has the fully synthetic stock so you don't have to worry about the elements, the mud just wipes right off. Any hog within 200yrds will drop right there using Hornady Superformance SST 140 gr. We have downed three with it.
If your brave and have your heart set on semi-auto, believe it or not there is a guy who hunts hogs with $169 Hi-Point .45, he takes them at 25yds max, usually around 10-15yrds from a tree.