I've no idea how long it takes to make a quality concertina and the cost of the materials and the resources needed (ie tools, workshop etc). The minimum time I've seen for a handbuilt fretted instrument is about four months plus waiting time and it is not unusual for it to be about 8 to 10 months plus waiting time. The number of instruments built might be in the order of 12 to 18 a year. How many instrument makers will get a good standard of living out of affordable instruments?