This may have already been posted elsewhere but wanted to pass along in case not.
We cache on a tight budget so cheap is our motto! I got tired of the GPS sliding off the dash or having to drive one handed but I was not going to fork out 30 some odd dollars for a mount. I found a cell phone holder at Wal-Mart for 4.92 that clips to the car vent and voila! My Garmin Gecko fits in quite nicely and it is adjustable.
Just thought I'd share.