We used the following unit this year for our custom controller:
http://www.u-hid.com/
If you don't need as many Inputs they also have the following:
http://www.u-hid.com/home/uhid_nano.php
Their web site is hard to navigate but they are really easy to program and have been good to us over the years.
Helpful links
Config Utility Download:
http://www.u-hid.com/home/download_driver.php
Manual (with good examples of wiring diagrams)
http://www.u-hid.com/u-config/u-hid%20Manual.pdf
Online Store:
http://www.ultimarc.com/JShopServer/section.php?xSec=13
Hope this helps,
-Clinton-