The problem with 800 Mhz is that it is such a short wavelength, the receiver becomes very finicky unless the antenna is resonant. The problem is that loss plays a role and even RG 6 quad shield becomes very lossy at lengths of more then 50'.
I guess if all you want to listen to is local traffic, which can be received with a handheld, then any antenna and coax will work. But if you are trying to receive signals from 30 - 50 miles away - forget it.
Cheap and good don't walk hand in hand when it comes to antennas and reception.
If it was amateur radio, I would invest in a good base station antenna, a Diamond X510 is a great antenna from a reception standpoint, as long as you buy one that uses an N connector, not a PL connector. PL connectors are not designed for use on UHF frequencies and they have an impedance bump around 300 MHz..
If all you want to listen to is 800 ish UHF you could probably try to use a UHF television antenna, although television antennas are designed for frequencies between 300 and 700 Mhz, so the antenna would be too long for good reception of 800 mhz, but if the signal is strong enough, even an old coat hanger will receive something.