08JKRHD

PARAMETERS

<300$

able to use as handheld

able to update

has trail maps

08JKRHD

no suggestions????????????

RedJK2

Many GPS receivers will fulfill your first three requirements. I can't think of any that will meet the last one while staying under $300.

ConroeJK

I bought my Garmin Trail Guide a couple of years ago on eBay for $300. Don't know if there are any on the bay right now or if they are harder to come buy now days. It's a great unit for $300, and has everything you asked for, with serious 20 hr battery life outside the jeep.
I did a write up a while back, I'm sure it would come up if you searched for it.

Rhino64

Go with the garmin, either the 60CS or the 60CSx about $180 for the CS and $200 for CSx. Buy a custom topo map for the state or states you need off ebay cost $30 bucks you'll have a little money left for mods.