These are very rare. Try putting Emu 6862 in as a favourite search on ebay. Make sure it searches all of ebay; when i did this search i found two boards in around twelve months, both were abroad and both were very expensive. Both cards sold before i could buy them and i ended up buying a second sampler with the board fitted. It turned out to be a good move because i now have an immaculate E4XT and it was only a little more money than a board would have been.
If you want to use the keyboard input, be sure to pick up one of these, as the old AT keyboards are quite hard to come by now.
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 3D1&_rdc=1