I have two new old stock 800 MHz antennas that can be used to improve 800 Mhz reception in fringe areas!
The antennas are the SEEKER along with an Antenex DEXE. The Antenex is tuned for 821 - 902 MHz. Details on the SEEKER can be found at this link: http://www.radio-ware.com/products/sek800.htm
The SEEKER sells for $59 new - and both of these antennas are new in the package. Both have BNC male connectors to attach to your scanner.
You can have both antennas for $50. Let me know if you have questions.