For the Advanced Evap, you can get NTK (P/N: 25044) or Bosch (P/N: 15630).
For the Bosch, i have found them for $65.99 @ Oreilly: http://www.oreillyauto.com/site/c/detail/BOS0/15630.oap?year=1999&make=Land%2BRover&model=Discovery&vi=1377806&keyword=15630
I have also found the NTK @ Summit...