It shouldn't be that expensive if you do the filter at the same time as changing the oil.

The oil is like liquid Gold - about $80 a bottle for 500ml from memory.

I'd get a quote from the dealer and then get price from a reputable VW independent. Sounds like the dealer is just trying to fob you off. You'll probably find the independent will be cheaper and may even know more about it (or at least take more of an interest)