The Garmin eTrex 10 and Magellan eXplorist 110 can both be had for around $100.
The first basic eTrex (discontinued, but available used) is what I used in Afghanistan and worked great. I also have a Magellan eXplorist 100 that I got on clearance for $50 at Walmart several years ago.
Since you are talking basic GPS capabilities I would check out clearance sections at all stores you frequent.
Used on eBay is a great way to find very reasonable prices on GPS.
I think the Garmins are more robust, on the Magellan eXplorist 100 I cracked the LCD screen on it. I was able to buy a replacement screen on eBay for $12 so no big deal during normal times.
I have an old etrex somewhere and it worked fine. I have a GPS 60 now and its a bit overwhelming as in a shit ton of function’s in a little package. It takes a lot of scrolling and tabbing to get places on the unit. Garmin is a bit tight on the maps too as in its tough to load third party maps if you don’t have technical knowledge. I’d take the advice on the Garmin line and look for an older one. I don’t have any experience with Magellan’s….
Have an etrex legend, didn’t work for shit in the trees. Bought a garmin 64st. The antenna helps it work even in dense trees. It even has a camera (I’m a search and rescue tech, gives coordinates of the picture).