Most mail-order nurseys have suspended shipping till spring- but here are a few websites I've ordered from:

http://www.gpdesert.com/ (good prices and if you order from the specimen page you get the exact plant in the picture).

http://www.bonsai-collectables.com/index.html (I order from them annually- the will send you pictures of a few samples to choose from if requested)

http://rareexotics.com/store/ (Plants from here have usually been larger than expected)

The next two I haven't ordered from but browsed the pics:

http://www.rare-succulents.com/index.htm

http://www.out-of-africa-plants.com/

Good luck