You would be able to purchase tomtom GPS antennas at radio shack, best buy, target and other electronic stores. You may also be able to find a tomtom GPS antenna at www.amazon.com/tomtom
You can purchase Terk antennas at your local Walmart, Target, or Best Buy. You can also purchase Terk antennas from personal sellers at eBay and Craigslist.
There are many places where one can purchase car antennas. One can purchase car antennas from popular on the web sources such as Auto Trader and eBay Motors.
Not all GPS units require an antenna, but they can be very useful when a stronger signal is required than the GPS unit on its own can provide. Antennas will work at their best when you are in remote locations and when the sky is not visible from your vehicle or place on the ground. http://www.maps-gps-info.com/gp-ant.html
you can purchase several puck style gps antennas that are usb, can be used with map programs. I have a delorme lt-20 with delorme street atlas, it's pretty nifty.
The short answer is no. A cell phone usually uses the carrier's antennas to triangulate the signal and provide the current position of the user; so when there are less antennas to triangulate, the poorer will be the quality of the signal. When there are no antennas, the cell phone won't be able to work as a GPS. However, if the phone does have a specific GPS chip inside, it will use satellites to give the position. Provided that there is not too much interference, it will work as long as the phone is powered.
There are a number of places where one can purchase a Tiger GPS. GPS Tiger, Calibex, and Price Machine all have current information about the Tiger GPS.
three basic types of antennas are: omnidirectional; semidirectional and highly directional antennas. typically when you purchase wireless access point and wireless NIC it has attached 2.14dbi omnidirectional antennas
One can visit any local electronics stores to purchase their raymarine gps units. Or, if more conveinient, one can purchase their raymarine gps online.
You can go to this website to purchase a quality GPS mount: http://www.bestbuy.com/site/GPS-Accessories/GPS-Mounts-Cradles/abcat0307026.c?id=abcat0307026
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.
You can purchase a hummingbird gps on the following website: http://www.humminbird.com/. They have a great selection.