VIPER is the statewide radio system... I assumed you knew something about it already since that was in the title of your original post. Many counties (including mine) use it as their primary public safety system while others (usually larger counties) go there own way and build/operate their own system. VIPER is a P25 Phase 1 digital trunk system - more or less the digital public safety standard.
DMR is one of several digital modes - mostly used by businesses - it is a lower cost option when it comes to going digital. DMR (and NXDN - yet another digital mode) is (are) used by some public safety organizations for various reasons - cost being one (as mentioned) but it could be for other reasons.
So - when if comes to a scanner, for basic minimal monitoring, you can probably pick up a new P25 Phase 1 radio (at times?) in the $250? range. However, keep in mind these radios will not handle DMR (or NXDN) - or P25 Phase 2. You may not need these additional modes - at least right now (simmsrep appears to indicate that the Roxboro PD DMR is simulcast on VIPER). From what I've heard, VIPER is going to remain P25 Phase 1 for the foreseeable future (even though they are slowly/gradually updating their licenses to permit Phase 2 as some point in the future).
That said, many will tell you that you should spend more on a more current and more capable scanner that does offer P25 Phase 2, DMR, and/or NXDN. It all comes down to how much you want to spend and what you really need. Just keep in mind a couple of things - Uniden will sell you a radio that does P25 (Phase 1 and Phase 2) but then will charge you more to add DMR capability (and other modes) as options.
You are probably looking at (low end) $425 or so for a P25 Phase 2/DMR solution.
The starting point for your decision really needs to be "how much do I want to (can I afford) to spend?".
As far as expense - the newer the model, the more they cost. If you want to keep the cost at a minimum, stick to the older but capable model(s). If you're willing to spend more, then perhaps go with something that is more "future proof" (but really isn't). On the extreme end, there's almost always something new around the corner that should be better - just be prepared to pay top dollar when that time comes... Note: none of the scanner/radio vendors tells you in advance if/when something new is coming -- usually not until it is ready or nearly ready for market - so the answer to your question "is something new coming soon?" - only the manufacturers know and they ain't talkin').
Decisions, decisions - and only you can make them!
