Hi everyone,
I wish to cut my iPhone data usage and believe using a satellite based GPS would help a lot. I am seeking a GPS that would offer turn by turn directions, that would be able to measure my distance covered walking or bicycling, stop measuring distance covered when I stop moving, have comprehensive US road maps preloaded, and let me upload maps for hiking or travel outside the US. If I can attach it to the handlebars of my bike that would be great. I am hoping to be able to buy the unit for $200 or less, gently used, on EBay or similar site. Can anyone recommend a model?
Thanks!

Garmin etrex 20.

+1 the etrex 20 is a nice GPS you could buy it new + a bike mount for less then $200. The included map is not great however you can add an SD card and load OSM maps for free. You can get standard road maps, bike maps, topo maps for hiking etc.

FYI: There are aps that allow you to download maps to your phone so that a data connection is not necessary or used for navigation.

Another eTrex 20 user. I have downloaded OSM maps and it works well. I keep thinking of getting a cycling specific GPS; but, frankly this one does all I need.

Thanks everyone. I will research the Etrex 20. I have a question. If I download maps to my phone & navigate without a data connection will I be able to get turn by turn directions or orient myself I get lost?

Yes. A GPS receiver calculates your coordinates from satellite signals. Most GPS receivers also include a map, which is a database of roads, intersections, points of interest, etc... and includes firmware that displays the map and your position on it. From that it can also calculate routes and provide turn instructions. A typical smart phone is capable of the same thing with the right ap and map data. For Android I have used OsmAnd for this. There are other similar android and IOS aps out there.

I have the older Legend CSX GPS but it works the same way. You do get turn by turn directions if you have the maps loaded. I purchased the maps from Garmin in MicroSD format.

Do yourself a favor and learn how to create routes online. A GPS will often give you directions that are fine for a car but not a bicycle. Making routes takes quality time using Google maps to view street level. However, you'll get much better results.

Also, there are GPSs out there that give you a "Bicycle" option but don't believe it. I've tested these first hand and they always put me on a road that may have been better but were still not great. Even Garmin's software will not direct me to the bicycle route in my town but the second fastest avenue.

I'm sure whatever you wind up with will be better than using a car GPS on your bike ... lol

Or, you could turn of mobile data on your iPhone while cycling. The GPS will still work, and it does not use data.

As a bonus, it will dramatically increase your battery life. I've ridden a Century and only had to plug my iPhone5 into a USB charger for the last 3 miles.

Correct, GPS does not require data, but the way mapping is implemented on phones requires data if you want a map depicted because map data nor navigation functions are resident on the phone. You need an app that stores the map data on the phone and has the navigation functionality in order to see a map and get nav functions without a data connection.

Unless you plan on riding a century, most maps will be cached adequately. OK so turn-by-turn won't work. Does anyone use that on a bike? I pre-load tracks into Cyclometer, the track is plotted over the cached map, it works great with no data.