Ok so firstly if you have everything you need then £300 to fit it is very expensive. Some people say they need adjusting and that might be the case but I have had 3 and each one has fit very well and they are easy to adjust - do not pay £300 just to do this.
However, to fit a hard top you need the fitting brackets - these are rare in the UK and will cost around £300 or more, not sure if you have them already or what the availability is like in the US? The brackets have a number of bolts and there are 2 torx bolts that are needed for the front - there is a standard BMW wrench to tighten them but a normal socket set with torx bit will work just as well. At this point the hardtop will FIT the car.
to make the demist work you need a button (prefacelift for yours) and a wiring loom. the loom is fairly cheap from BMW, but the pre-facelift button is £120 for BMW in the UK !!! If you have an electirc hood then the loom is easy to fit/find. if you have a manual hood then the loom is tucked up under the carpet behind the passenger seat under the window. The button loom is tucked under the rear console pocket/switches.
After this there are additional trim pieces that go over the brackets to make it look cleaner and neater etc and these are harder to find 2nd hand.
All in all its easier than it sounds. PM me if you need more info - i think they radically change the look of the car.....
