PLUSHPIG.COM - A simple webpage that apparently shows someone's collection of pigs. They look quite old, but still nice!
PigCollecting.com - A quaint website selling pig gifts and figurines. It has a links page with many resources.
Pig's Whisper Country Store - A shop in the UK selling a whole lot of pig-related items. Nice picture of their plush items here.
Of course many more piggies can be bought from the likes of Amazon.com, Ebay, NexTag, Shopping.com, etc. And, of course, Google. Just use "Pig" and "Plush" as keywords.