If you have a mobile phone which is Sony ericcson or a Nokia with GPRS enabled,you can use the phone as a GPS unit by downloading the software.It will use the GPRS connection for accessing the Map onto the phone for that you to have an internet connection on your mobile phone.
Cheap GPS units usually don't react as quickly as premium ones. Also, depending on the service, the cheaper ones do not have options to find food or entertainment.
stores like factory direct and liquidation centers
The best place to find cheap GPS devices is on eBay. You can also check out Tigerdirect, which often has great weekly sales on GPS devices. Overtock.com will occasionally have good deals on TomToms as well.
Right now, Walmart appears to have a pretty cheap tomtom gps: http://www.walmart.com/ip/TomTom-XL-350-4.3-Portable-GPS-Refurbished/15185477?sourceid=1500000000000003142050&ci_src=14110944&ci_sku=15185477
You can find a second hand Extrex GPS at online stores such as Amazon or eBay. You can also find one on NexTag or ukrocketman. NexTag or Amazon are your best choices, because you will find a variety of different Extrex GPS handhelds at cheap prices.
You can find cheao GPS navigation systems by going to www.gps-practice-and-fun.com/sprint-nextel.html.There you will find GPS systems like TOM TOM and garmin nuvi.
If you have a smartphone there are actually cheap or free gps logger apps that will let you record your marked locations. These marked locations can then be used for various purposes such as mushroom hunting or fishing spots.
If your are looking online, amazon should have a cheap car GPS system. If not go to an electronic store like BestBuy or Staples. Walmart and Target should also carry them.
A cheap gps system would be one that only gives you routes to the place you are looking for. Price wise any gps system under one hundred dollars is considered cheap.
You could find a gps running watch at amazon.com. Amazon is a great website because it provides people with a large inventory and items usually come for a cheap price.
The Garming Forerunner 205 is a great GPS running watch that is very inexpensive and available through amazon.com. This information is from runnersworld.com
Depending on the type of GPS antenna you are looking for, starting a search on amazon.com or craigslist.com might be a good way to find cheap GPS antennas. Be warned you might have to do lots of searching for the correct match and best price. Otherwise checking out local technology store websites and sale papers like for Radio Shack or Best Buy are also other options to finding an inexpensive GPS antenna.