I don't know that one exists. I would say your best bet is looking through the "sold" eBay listings, as well as the completed ones to see what certain pieces are going for and which get relisted for overestimating the current market value.
Thanks for the advice I also have been guesstimating the prices through sold auctions on ebay but thought someone might have created a Price Guide at least for the older pieces that deserve it.
Anyone know of anywhere that might show prices of older pieces? Limited quality created pieces.