I was indeed referring to the brake reaction bushings. £300 fitted for new arms AND those bushings is about fair, if it's just the arms you're paying approx. 2 hours which is double what I expect it to take a garage.
It doesn't sound like you're in a position to DIY so if you want it done then you'll have to suck it up. Equally it's only slight play so could wait, you may find a local member who could help you out.