The problem is that when you need niche books and order them through small local stores it can take months before you get them. Recently got an e-mail that a book I ordered almost a year ago was available for pickup. Not sure why it takes them this long.
Similarly I ordered a spare set of strings for my niche musical instrument through a local music store 4 months ago, have called them at least once a month and it still hasn't arrived. Ordered them online from a German store, it arrived within 5 days. The excuses I've heard are: 1. they forgot to add it to the order 2. they order from many different suppliers and depending on the volume they will "collect" more orders from customers for a single supplier to keep delivery costs down, and for suppliers of niche products this can take a while. 3. It might have arrived at their warehouse but not at the shop. As a musician with concerts planned you can't just keep waiting for spare strings, you need them then and there before the concert.