There's one on eBay. The picture is for a
Ruby slot-loader, but the description says "strawberry" 333 MHz, which is a tray-loader. Search on "imac strawberry" to find it.
I'd keep an eye on eBay and craigslist.org (for your area). Also, LowEndMac.com has an email list for Mac-centric buy/sell.
http://lowendmac.com/lists/swap.html