As a comparison, Henderson Co NC runs a multi-site NexEdge system also, and it sounds like Pickens Co will implement something similar. Henderson Co continues to run their conventional analog fire paging transmitter, and I assume that's to handle volunteer paging.
Polk Co NC also runs NXDN in "conventional" mode (not a trunked system like NexEdge). To my knowledge they no longer provide analog conventional tone-out. Perhaps they're depending on the CAD system to send SMS text messages to volunteers? Not sure how that impacts things like ISO ratings.
The cost difference between P25 and other digital modes is real, and in many case, really BIG. But there are some compromises that come along with those other digital modes and the corresponding cost savings. It's a shame that the State of SC isn't able to do more to help defray the cost of joining Palmetto 800 for these smaller counties, as the state's interoperability plan depends on agencies being on or at least having access to Palmetto 800. I guess when Motorola operates the system, then they set the pricing? I'd be interested to know how those relationships work (between the state, Motorola, local governments and other P25 vendors and manufacturers) and what options are really available for alternative P25 solutions.