What is the best handheld GPS for under 100$?

You might want to list what your expectations are for a GPS receiver. For example, there are mapping GPS receivers, and they have an internal database in memory. In some cases, this is a road map. In other cases, it is a crude topo map. In still other cases, it might be a nautical map. In some models, there is no built in database, and you have to transfer files from a disk through the computer to your receiver. In other models, it comes with the whole database from the factory.

Some receivers are optimized for car use. Others are optimized for hiker use and internal battery power only. Some operate on two AA cells. Others require four AA cells. In general, running a fancy color display will use up your battery power faster than a plainer display.

Some receivers can accept an external antenna, and some cannot. If you want to operate it in a car, often it is good to have an external antenna, or else you have to position the receiver pretty close to the windshield.

For years, Garmin has been the consumer market leader.

–B.G.–

Well I want to use it for when i'm backpacking and I lose the trail or whatever. Basically I want to be able to use it in the backcountry. I understand that tall trees and metal can interfere.

I want to be able to put maps onto the GPS. I don't want outdated maps. I want to have the option of using AA or other batteries. I want color.

http://gpsinformation.net

This is probably a good resource to learn more about the various receiver features and choices.

If you try to receive satellite signals when you are standing under a dense tree, it might totally block the signals, or it might only impair them slightly. Some receivers are a little better than others in this regard.

Metal, per se, has no effect on reception. If you have large flat metal surfaces near the receiver antenna, that can cause "multipath interference," and that can produce some strange results. However, you generally only get into that if you have your receiver around metal car bodies, metal flashing on a building, metal signs, etc. I've seen people struggling to remove a metal belt buckle because they feared it was interfering (NOT). As a general rule, you won't get nearly as good of a map showing up on that tiny little display as compared to a printed paper map carried along with the GPS receiver.

So, many of us do the "mission planning" (the military term) at home on the computer, and we produce a paper map based on our route, and that has waypoints (data points on the map). The waypoints can be transferred to the receiver via cable. Then, when you are out on the trail, the receiver can point you along from COE1 to COE2 to COE3, etc.

I've operated industrial GPS receivers since 1994.
–B.G.–

Garmin Geko 201: "so light you can't leave home without it"

http://www.google.com/products/catalog?client=safari&rls=en&q=Garmin+geko+201&oe=UTF-8&um=1&ie=UTF-8&cid=8271546469448092117&ei=ZTRsS-OKNJ6XlQeLksWeBQ&sa=X&oi=product_catalog_result&ct=result&resnum=3&ved=0CCAQ8wIwAg#ps-sellers

Garmin Foretrex Models

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Will a color screened GPS show creeks and ponds?

It will show whatever is on the maps you load on it. Some can show satellite imagery.