I put in my own Frigoboat system a few years ago. Parts cost was a bit over 1K with the 'keel cooler'.
There was also the haul-out cost to install that heat transfer thru hull ('keel cooler'), but that added nothing extra to my regular haul out cost for bottom painting.
Since our boat had never had refrigeration before, I did waste quite a few hours planning the routing for the tubing and fabricating the compressor mounting, running the new wiring, etc.
Costs are up quite a bit these days, but unless you insist on paying strangers to do the work I doubt you could spend more than, say, $2k, to put it in round numbers.
Nice thing about doing your own installation is that you have personal knowledge of all the parts and how they work together.
OTOH, if I were wealthy, I'd probably pay someone else to lay on their back and work under the galley counter!
It is both very quiet and efficient, using few amps when running.
Here's to cold beers again in your future!
ps: quick edit.... must stress that my choice in fridge technology is not meant to denigrate the Adler Barbour. I met one sailor that had 15+ years continuous use on his A-B system before it gave up. I just realized that the thread title sort of implies a competition with a potential winner and loser...
pps: Any of these systems are considerably less spendy if you opt for air-cooling, also.