GPS Mounted on atv ?

[RazBarlow]

Just wondering, my son and I are planning a big trip next year on atv's. I was told to get a handheld GPS unit and mount it onto the bars of on of the atv's. My dad has a Garmin Etrex that he got from aldi foods but can't find a model on it . He said that he would sell it to me cheap. Does anyone own a gps mounted on their atv ? Does it ever help them out or can help usually be found ?
Thanks,
Raz