Yamaha MY8-AT ADAT card in excellent condition. Here's a link to the eBay listing. $199 "buy it now" with $150 reserve.
RME Digi9636/52 PCI card. Two sets of ADAT ins/outs. This is an older card that pre-dates the Hammerfall series. The latest drivers are for Windows XP, but some people claim to have gotten it to work under 32-bit Windows 7. Works great if you're using a XP-based SAC rig or DAW. Asking $25. Free shipping CONUS.