Competition is fierce this holiday season in the portable navigation device (PND) market, as evidenced by the top brands aggressively pricing their products. (See “Countdown to Black Friday: Best GPS deals.”) Beyond door-buster deals, TomTom is taking a new twist on gaining market share; it is offering to purchase an older unit from customers who buy a new one through tomtom.com. Think of it as a version of cash for clunkers. (This cash for gadgets campaign shouldn't be confused with the "cash for appliances" initiative.)

Once they place an order for a new TomTom, users can then use an estimator to determine the trade in value of their old unit, send it in, and in 7-14 days they will receive a rebate check. The TomTom iPhone app is not eligible for this program. 

The program will likely drive sales, and even convert owners from competing brands. It may also have an environmental benefit, encouraging people to trade-in units rather than toss them in the trash.
 
The program is administered by Dealtree, a company that refurbishes and resells products on eBay and through other auction Web sites. Naturally, this may mean more pre-owned GPS devices may be available online. It is worth noting that the batteries are not replaced during the refurbishing.
 
Customers can receive an estimate for their trade-in value using a simple set of pulldown menus at tomtom.com. Simply choose the brand, model, condition, maps included, and indicate if the product includes an AC charger, DC power cord, car mount, and manual.
 
Looking up sample products, the list is quite deep, though there are some holes. For example, the popular Garmin Nuvi 205 is not an available choice, though there are many other navigators spanning several product generations.
 
We checked several units and found the estimated trade-in value, including a prepaid shipping label, to be quite generous. For instance, a Garmin Nuvi 205W in good shape is valued at $62. Were it in excellent shape, it would be worth $65, and poor is still valued at $47. Those figure seem particularly high when compared against the Black Friday deals we found online. For instance, Best Buy is offering that device new for $100.
 
However, the program is based on purchasing the new model at full price through tomtom.com. Again, we looked up several units to assess the deals. Target will offer the XL 340 S at just $97 (admittedly a screaming deal), whereas the same device is $250 at TomTom.com. We found the Go 730 listed for $175 at Best Buy and for $350 at the TomTom Web site. Admittedly, these retail examples are extreme Black Friday prices, but they do highlight the need to double-check offers before taking the plunge. (See "Black Friday GPS deals online.")
 
For a quick reality check, we find the XL 340 S listed at $160 and the Go 730 at $150 at Amazon.com. Clearly, prices vary.
 
The key thing is to focus on the best units for your needs, then pursue the best prices. To do otherwise risks getting a great deal on a product that doesn’t meet all of your needs.

For more information on portable automotive GPS navigation systems, see our Ratings, first looks, and buying advice and watch our video guide. Discuss GPS devices in the forums.

—Jeff Bartlett