My backup GPS is an iFinder Go. It was obsolete when I bought it and cost only $25 new. My primary criterion was long battery life. The Go will operate over 40 hours on two AA alkaline batteries. It doesn't have the features of the current crop of handhelds. Heck, it didn't have a lot of the features of handhelds at the time. But it had the ones I needed.

Then again, my cell phone is only a phone and it's older than my iFinder Go. But it, too, has all the features I need.