Hi,
A while ago I bought a GO720, complete with accessoires (charger, dock, TMC-antenna, case) for about 80 euros. Seems a good deal, considering the general idea on this forum is that this device is good candidate for all sorts of navcores/bootloaders/upgrades/experiments, has a SDcardslot and 64MB RAM.
The navcore was 8.398 and the bootloader 5.5120 when I received it.
Everytime I put the device on the dockingstation/connect with PC via USB-cable the device frooze ...