I probably didnt make my comment clear enough for you regarding Linden, That was their pedigree in respect of the X, and then in turn your question on life cycle issues.

There are other options as you said Dinan - there is one authorised dealer over here as well as Hartge, also Hamann franchise some outlets over here and there are a couple of bespoke designers and installers.

As for prices on the X, I cant say as most will negotiate at point of sales even on advertised prices.

I have also seen a couple of NOS kits which might be an option.

Good Luck.