It is not that difficult to fit one yourself. Time consuming and care must be taken (measure three times cut once etc.) Fitting is quite expensive due to the time it takes. I think a lot of people are put off doing it themselves because of experience with modern convertibles which are far more complex. supercass
I was lucky enough to buy a genuine new one on ebay - we fitted it in an afternoon....no great hassle. We didn't use 'poppers' at the side - velcro is much neater - and no holes to tear - which is all that was wrong with my old hood.