I used to have one, and sold it earlier this year for $75 on www.OffshoreBid.com with a swivil mount for an extra $5 bucks. I may have used it 4 times and never used the mount (everything was in the box).
The unit is slow because it is older technology compared to what is out there now. It uses the G-Map plug-in map chip for any kind of detail. The price seems to high for 5 year old design. I bought mine in Sept 1998.
I recommend NOT getting it and keep shopping.