Elektron Enterprise Edition is a $749 WPA-Enterprise server with directory support: The folks at Corriente Networks first released their Elektron Server for small- and medium-sized businesses in January, receiving accolades for offering full WPA-Enterprise support for $250 for both Mac OS and Windows systems (the server runs on both; it uses standard clients).
The Elektron Enterprise Edition adds external directory support through LDAP, SQL databases, and even existing RADIUS servers that don't support 802.1X. This last option is a great way to preserve legacy implementations and yet layer secured wireless services on top. It inserts WPA-Enterprise as a thin wedge instead of a complete replacement. (Elektron passes the inner method to the RADIUS server and handles packaging the outer PEAP or EAP-TTLS method.)
This edition also support basic RADIUS protocols, so it can be used as a thin RADIUS server for other systems for authentication, centralizing it. It also has support for policies, such as allowing particular users to authenticate only at specific times.
A 30-day free trial is available via download.