That's the current price for blades? I once got them for £25 from TPS, next time round was £46 with trade discount!
Worrying that a dealer says they can't get them, maybe complain to Audi UK?
The originals are SWF - you can find them online - many brands/ebay/aliexpress but pretty much always LHD - they fit but would lift at speed instead of pressing down.
Related but not Audi - have you seen the current Mercedes wipers - they have had these for a few years now...
https://www.youtube.com/watch?v=07AZHkkLR0k