This is a real tough question to answer, believe it or not.
First the easiest part: There are no cheap scanners that will deal with digital signals - they all are costly. Depending on some "things" you could get by at $370 to as much as $500-600.
If they are going to a standard Project 25 digital, then you can get by with the lower cost Uniden 325P2.
If they are going a different route, such as DMR (aka MotoTrbo) which is what the database shows for EMS dispatch, you are looking at the Uniden BCD 436 HP with its base price of $490. On top of that you have to purchase the upgrade for that "flavor" of digital. That costs $90. (All prices are off the Scannermaster website).
There is another type of digital, that being NXDN. If they are using that, you are looking at the Uniden 436 with the NXDN upgrade.
So you really need to be sure just exactly what they are using so you don't buy the wrong thing.
I suspect you are fairly new to digital. Just like you have different kinds of screws (SAE, fine thread, coarse thread and metric) there are different types of digital. It's not easy to find out which specific type is in use. The average responder may not be "tech savvy" enough to know, so you probably can't grab the next one you see and ask them.