A sow can produce two to three litters a year. Each litter will be six to 14 piglets typically. Are you ready to up the ante in how many you raise or sell the extras. They sell best in the spring, which is when you'll want yours too so you don't want to sell them then. Late summer and fall piglets don't sell well as live piglets but they sell fairly well as suckling roasters.
She's expensive to feed if you're using grain or a commercial feed so her litters are what pay for her. Sows get big - ours top out at about 800 lbs. This means they eat a lot too. It takes extra calories and food for gestating and nursing. Pasturing can help reduce the feed costs.
To breed your you'll need to borrow a boar or do AI. It isn't hard but you got to time it right in both cases. Borrowing a boar risks bringing in disease. Generally the stud fee is about $150 or so plus you have to feed him. Last time I looked at AI it was about $150 per sow, that was a few years ago. Remember to get two doses of sperm - you want to breed her twice about 12 to 24 hours apart. The other option is owning your own boar - he's expensive to feed and isn't really worth it until you have six or more sows.
Figure out your costs. Do a little mini-business plan for yourself. If you're doing a half dozen pigs a year it will likely be cheaper just to buy weaner feeder pigs.
Cheers
-Walter
Sugar Mountain Farm
Pastured Pigs, Sheep & Kids
in the mountains of Vermont
Read about our on-farm butcher shop project:
http://SugarMtnFarm.com/butchershop
http://SugarMtnFarm.com/csa