Well, you could probably find a used 396XT on Ebay, Amazon or even your local Craigslist for around $150 or perhaps less. Be ware, however, that buying used scanners can be very dangerous if you don't know exactly what you're buying. I got burned several years ago buying used dirt-cheap used scanners that seemed to work fine (i.e. they powered-up, the displays worked and they passed audio). However, a few days later when I started programming them I realized the RF boards were fried from de-sense.
All that being said, you will have to spend several hundred dollars for scanning P-25 trunked systems. I'm not sure anyone can give you an exact minimum dollar amount. You might consider a
Whistler WS-1040, I've seen a lot of good reviews on it. This unit is probably on the low end of the price spectrum. Also be warned, if you've never programmed scanners with P-25 trunked systems, you will have to read-up on the subject, there's a bit of a learning curve involved.
Alternatively, you could also scan P-25 systems for much less with two (2) $20.00 RTL SDR dongles, DSD+ and a windows computer.
