recently bought the 4motion valance for my 115pd from vdub garage for about ?38. That is also black plastic. So if this one that you are talking about is also black plastic and not body coloured like the anni one, just the same shape as the anni one then im sure it could just be ?35.
Yes it isnt the same shape as the 4motion one, but they are moulding the same amount of plastic so will be a similar price.
The black plastic that is standard on most golfs will be a lot cheaper to produce than the material that the anni one is made out of, hence i believe it could be the correct price, its just obv not gonna be quite the right look because not body colour but as we all know you can still colour code it, just a bit more effort.
Thats just my tuppence worth mind