Speaking as a former maker of R.Morse & Co concertinas at the Button Box (and as someone who has had a good crack at playing the Clover and Rose models sold in the BBox shop, as well as having a good look at their construction inside and out), I've been eyeing the latest releases from Concertina Connection - the Minstrel and now the Busker - with great curiosity as to how their prices are so much lower. Please note that 1) I haven't had a chance to handle, play, or examine a Minstrel or Busker, so all I can do is speculate; and 2) I'm a former (not current) Button Box employee, not speaking for the Button Box or R.Morse & Co in any official capacity.
The website spells out a few things, most notably that the Minstrel and Busker bellows are of a different construction. I'm not entirely sure what that means as far as how the instrument plays and feels, or how it breaks in and holds up over time, but it does clearly account for a chunk of the price difference. And the Busker is obviously cheaper than the Rose partly because it has fewer buttons, but the Busker and the Albion are about the same in button-count (while the Rose and the Geordie are about the same in button-count).
While differences in components other than the bellows may also play a part in price difference, my speculation is that the bulk of the cost savings is labour: Morse concertinas are made - stem to stern, assembly and almost all components - in Massachusetts, with very few exceptions (Italian reeds being the main one). Most of what enters the Button Box is raw material sourced (entire animal hides, sheets of brass, etc) from within America; most components are fabricated in house; and the ones that are outsourced are outsourced to local master craftsman like Al Ladd who work closely with the Button Box.
My understanding is that the Clover and Rose are assembled in America but some of the components are made elsewhere and shipped to America; and my speculation is that Minstrel and Busker are entirely or almost entirely made outside America. (Anybody who has information about this to the contrary, please inform us and I will stand corrected!) This would substantially reduce the cost of the Minstrel and Busker and likely account for a majority of the savings. On top of getting a great instrument when you buy a Morse, you are supporting a small local business (~10 employees), local craftsmen, and local and regional materials suppliers, and that costs a good bit more than Chinese labour; there's just no way around that.
I'm not trying to make a political statement or attach an inherent value to this; I'm just pointing out the economic reality that's probably partly responsible for the large price differentials here.