GPS tracking for an impulse-control teen

We'd like #1 to travel further afield on his own, but we have reason to distrust his judgment. So we'd like to be able to track him.

At one time I thought we'd be able to use a smartphone tracking device, but the same judgment issues that limit his independence mean data plans are also problematic. I don't know of any smartphone that would support gps tracking and robust data access controls.

So now we're looking into dedicated gps tracking devices. The market for these devices tends to be prisoners, demented persons, children of anxious or wealthy parents, special needs kids, dogs and high value goods. So a bit of a niche marke. The devices typically need some sort of data plan; the real costs are the data plan costs. I don't know of any devices that work with, say, Google Latitude.

I'm unimpressed with marketed items like the Amber Alert GPS Armor and the Spark nano 3.0 GPS tracker The dog GPS trackers are a little more interesting, such as:

• Tagg-The Pet Tracker Master Kit: one year service about $8/month. So-so Amazon ratings.
• Garmin GTU 10 GPS Tracking Unit: GPS & Navigation: $100 for 1 year service, so $8/month. Very poor Amazon reviews.

Using "Tagg" and "Garmin" as keywords I was able to find some relatively interesting discussions (the baseline Google results were SEO-scam infested).

• The Ultimate GPS Child Tracking Buyer's Guide (GPSmagazine.com): They liked the "WorldTracker GPRS" at $830/year (wealth market) or the Amber Alert GPS for $20-$30/month.
• Tagg the Pet Tracker Review — The Gadgeteer: Software weak.
• GPS for Pets - Consumer Reports: as above, nothing impresses

My overall impression was there's nothing good on the market at the moment. The Tagg device is probably the least bad.

So now I have to consider plan B again -- is there a way I can make his iPhone work ...

Update 6/2014: U.S. Will Finance Devices to Track Children With Autism (1/2014). Justice department, I don’t know if this is in place federally. Since I wrote this article in 2012 Find My Phone has become much more secure, so a minimal data plan with Find My Phone would work on iPhone. 

More significantly, there’s an entire site dedicated to wandering management in autism. Look there!