For context, see this thread:
Back by popular demand and a work in progress...sticky maybe? Whelen Serial Communications Primer Here and there, the topic of the Whelen serial controlled products comes up. I am writing this to provide as much information here as possible to make it a little easier to understand what it...
elightbars.org
I've purchased a few MCP01s in the past few years within a price range of $90 to $30. The $90 unit came with a promise from the seller to program it for my lightbar at the time.
I'd imagine those willing to pay the highest price would be those who recently purchased some B-LINK equipment and are in immediate need for a controller to get it working. They're likely also going to prefer a seller who can program it for them. Otherwise, I'd imagine potential buyers to be just those looking to purchase a spare unit if the price is right.
W/R/T BL627s, there were two varieties over the years. Later variants included some mechanical siren simulations. I believe they're apt to fetch a bit more of a price but not _that_ much more ($30-$100 range).
Also, my perspective is very narrow. I dig the B-LINK stuff and very much enjoyed tinkering with it.
Obviously, there are (or were) others here on ELB who know _alot_ more than I do as far as actual use in the field, and current market conditions/pricing.