It is the real world of retail. If you sell something like guitars that cost hundreds, there is the risk that you will be carrying thousands of pounds worth of stock indefinately. The money is to be made from moving stock rather than warehousing it so the pressure is on to find some products that move quickly to support your main operation. For a music shop it woudl be strings, straps, fast-fret and plectrums etc My kid brother opened a Harley garage in Chepstow with a view to working on bikes but he now mostly sells biker related clothing. I have spent time at his shop and seen, at the most, one or two bike related transactions but a dozen pr more purchses of jackets, boots etc. I guess most musicians own one, two or three guitars but a couple of dozen t-shirts. More transaction is less warehousing costs so the best plan is to sell lots of things cheap rather than hardly anything expensive.