To echo what others have said, ask some questions and find out what exactly you're getting. If it's heritage breed, pastured pork, $5/lb is not outlandish at all. If it's crap breed, pastured, raised by the local guy then it might be too much. If it's crap breed raised in similar style as commodity pork, but still by the local guy then it's definitely too much.
All the comments on $.99 or really anything under $2/lb are almost certainly factory farmed commodity grade pork. And while I buy this most of the time too, you certainly get what you pay for. Which, in this case, is almost no "pork" flavor, a scourge on the environment, etc.
For comparison sake there is an awesome farm couple here. They raise pastured chickens/turkeys, have the best eggs I've ever eaten, and they also raise pastured Berkshires. They recently have added enough pasture to have a beef herd as well. Their price for pastured Berkshire Boston Butt is $6.50/lb. Picnics go for $5/lb. I do think that their prices tend to be a bit higher than other pastured, heritage breed vendors, but the quality is excellent and they're awesome people.