My experience has been that ALL speaker manufacturers charge quite a premium for drivers. It is one of the only ways they have of protecting intellectual property rights. It's pretty easy to reverse-engineer the crossover and enclosure; not so easy to reverse-engineer the drivers. The only way to avoid knockoffs (aka somebody stealing and profiting from the significant investment already made in research and development) is to control at least one critical part of the equation. For loudspeaker companies, that piece ends up being the drivers.
Personally, I have no problem with Axiom's policies or pricing in this area, and have absolute faith that they would deal with me fairly if I ever needed service.
A compromise to this and to be able to still deliver reasonable priced modifications (product support) to past versions is to only
sell these upgrading parts ( crossovers, drivers, tweeters etc) to existing customers only that can be verified within their system
. All customer and product information is in the company system - what you ordered, how much, name, address etc. Even at a more reasonable rate you can have policy to ship the old parts back to the company when the new ones arrive. If the prices were lower, that type of policy seems very reasonable to me. This is one way you can still offer excellent product support at good prices, without alienating your existing customers as well as protecting intellectual property at the same time.