Purchasing GPS receivers is something that should be planned.
As the purchase is significant, even with the cheapest GPS receivers on the market, you will want to ensure that you are getting the best price possible.
In order to do that, you will need to carefully evaluate each GPS unit and learn about the types of features it has and how the features further your investment.
The easiest way to learn how to properly evaluate GPS units is to compare the Garmin Street Pilot III with the Magellan Road Mate. Both of these units are around the same in costs and functionality, although there are several differences between them.
The Garmin Street Pilot III has a higher learning curve, but can give more information quicker -- if you know how to access the information. The Magellan Road Mate is easier to use, but does not give quite as much information on your location. Both products come with a wide range of maps and tools to help you get to your destination safely.
When you are making the decision between them, it resorts to how the features function and what brand you like the most. Finding this information out is the core of a basic evaluation.
A Homemade GPS receiver is another option you can consider. While many GPS receivers are not homemade, if you have the skills to craft one of your own, you can get the exact features that you desire. However, you should keep in mind that you will not benefit from customer support, or be able to have all of the features of a store purchased GPS unit.