How much is a digital police scanner?

Scanner's vary in price.

There are digital and trunking and analog scanners that come in the forms that can be hand held or mobile or base units.

Depends on the brand name and the type of unit.

Their are manufacturers that sell new scanner's such as Radio Shack and Uniden.

Other places such as an auction website such as eBay or places that help people sell items such as Amazon may be cheaper since some of the purchasable equipment may be owned and used by a person or persons.