You have two Ethernet modules:
ENC28J60 Ethernet LAN Network Module
W5200 Ethernet Module(Gadgeteer Compatible)
one is almost 4 times dearer than the other, why would I choose one over against the other?
I want to be able to set up for both 10M and 100M speed and use SPI interface to Arduino.
What is the expensive one offering me which the cheaper one is not?