I've just bought a set on eBay for £19.99 including Hermes tracked delivery. I know you can get cheaper blades but of the ones I've tried, they don't compare to Bosch. I paid about £25 for the last set which I fitted 10 months ago and they still wipe like new. Search for Bosch A427S - the seller says they only fit Nemo and Bipper, but we know different .
I can't find a reasonably priced rear blade though.
I can't find a reasonably priced rear blade though.