A good site for ordering a deumidifier is:
http://www.dry-it-out.com/dehumidifiers/car-storage

They are also helpful if you want advice, and they helped me sort a warranty issue with no fuss.

I have a DD3/DD322/Xdry Classic Desiccant Dehumidifier, great unit and removes a staggering amount of water all year around. Cost about £210.

Aero 8 GTN #11

"What we do in life.. echoes in eternity."