Ebay is just great for building up your collection of piggins. I bought an ornament for £4 new in box and when it arrived the price was still on the box and it cost £11.50, what a bargain! You also get great deals if you buy a set. If you end up with a double you can always sell it back on. Even if buyers don't say that they give you a postage discount on multiple buys, if you ask they are usually likely to give you a little bit off.
I highly recommended buying your piggin's on ebay as you save so must more than it would be to buy them in a shop.
Picture at the top is of Piggin Tantrum which I got for only £2.50 inc p&p