There are a few available on Yahoo!Japan auctions, but as for brick&mortar stores it looks a lot like a GachaGacha toy (the things you put money in and then turn the handle to get your toy to come out). I would say you should look in Akihabara - they should have GachaGacha only stores as well as places that just have weird items and should carry this It also seems like something Kiddy Land might carry: http://www.kiddyland.co.jp/en/stores.html

Here are some auctions with good pics:

http://page12.auctions.yahoo.co.jp/jp/auction/p90435481
http://page15.auctions.yahoo.co.jp/jp/auction/t56273846
http://page17.auctions.yahoo.co.jp/jp/auction/v37649677

Edit: An interesting thing to note, the golden pig has it's own traveling blog :
http://www.lokuloku.com/blog/