Go to the Radio Shack that is part of LaPlata TV on 301 across from Walmart, they will program it for you. You will get Charles County, St Marys, PG County, DC. If your not interested in all the other counties its very simple to block them out.
They sell them for $499.00, and are about the only place that sells the digital scanners that I know of. They do go on sell sometimes $50.00 off and around Christmas and Fathers Day they were $100.00 off.
I have always listened to a scanner and when Charles County changed their radio's earlier this year or maybe it was late last year I about went crazy, could pick very little up and being a member of a fire department in the county and having two family members who are police officers in the county, I am use to always having one on.
I finally broke down and bought one back in the beginning of July after someone told me they were $100 off for Fathers Day sale, unfortunatly I came in one day late and they were no longer $100 off, but were $50 off so I went ahead and got it.