Renault Clio noisey especially when going faster

Last few weeks my Clio has been getting noisy particularly when on dual carriageway or motorway , especially noisy around 3000 rev @ 60mph.

I checked tyres, exaust, doors, trim, manifold bonnet and hatchback but found nothing (checked oil and water powersteering and petrol just for luck).

Took to local Renault Dealer/Garage and they 'suspect' its the rear wheel bearings which they want £150 + vat to replace.
Can anyone confirm that their diagnosis is likely to be correct and tell me if £150 seems reasonable (it seems very exspensive to me but I doubt I am capable of doing it myself) can anyone recommend anywhere I can get a repair at a more reasonable price?

Thanks
Steve