I am wondering what a base model GPS unit costs for my bike? Id like it for commuting around to places Im not sure where they are and keep track of mileage. I ride fixed gear so cadence isnt a big deal, neither is heart rate or such. Id like it compatible with Strava.

If you have a smart phone, don't ride terribly long, and don't ride in the train, start with your phone. Use the Strava app, or Google My Tracks (free) to get started. Those will give you speed, distance, moving time, and a map of your routes. At some point you might decide to spend the $200+ on a high end unit but you might not.

Cateye stealth evo is a fine gps unit with a truly crummy manual that runs $130; you should be able to pick up the older cateye stealth 50 for less since it is, I believe, being discontinued.

Cycling GPSes with street maps include Garmin models Edge 705 and up. Sometime I see big discounts on the Garmin Edge 800 models, which are a generation behind but still have plenty of capabilities. The current Garmin models with street map capabilities are the 810 and 1000.

The Garmin Edge 500 model has a lot of features, but no street maps. You can load it with road courses you can follow, but with a comprehensive street map of an area.

To get street maps in a Garmin cycling GPS, you'll pay over $200 (on a great sale) to get a new but older model like the 800. Secondhand models are obviously cheaper.

Starting with a smartphone is a logical option. Many cycling apps will track your mileage and give you street maps. If you already have the smartphone, use one of many free apps such as CycleMeter for iPhone. RideWithGPS, MapMyRide and Strava are among the other options. With a smartphone, you'd just need a good case and mount to put the smartphone in front where you can see the maps when you want.

The cycling GPS devices are marketed towards riders interested in performance metrics like heart rate, cadence, power, and in tools such as interval workouts.

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I'd recommend either a Garmin eTrex 20 or 30. You can buy them new or used for under $150 and get more functionality than most people use/need. The 30 can be augmented buy the GSC-10 to provide cadence/speed sensors and can also be used with an HRM. Both use AA's that provide over 18 hours of use without being swapped out (some people claim over 24 hours use, but that's really stretching it in my opinion).