Our sister business Cycad Connections has a website dedicated to cycads.

There you can find images and plant sizes typically available for the following, as well as a full collector's cycad list:

Cycas revoluta - Sago Palm 
Cycas taitungensis
Dioon spinulosum and mejaei
Zamia furfuracea - Cardboard Plant
Encephalartos trispinosus
Encephalartos dyerianus
Encephalartos horridus 
Encephalartos lehmannii 
Encephalartos middleburgensis