Accordions are not cheap instruments. Even cheap ones are not cheap. If you manage to get a decent brand for a few hundred dollars or less that is playable, you won the lotto as far as I'm concerned. Take into account the limitations of where you can purchase a WORKING accordion and it becomes a supply issue.
When I worked at LB, there were 9 other employees, that's a lot of overhead in payroll alone. There are also two other factors that afford LB they're prices: every instrument sold has a repair warranty and the fact that it is a proper brick and mortar (say what you will about that but it adds a certain level of legitimacy to the establishment that someone like myself, working out of my house, has to work a little harder to earn).