how much is a rear wheel bearing kit for an escort rs turbo?

need to get mine done, just one side, to get it through the mot. to save time, i thought i'd pick the kit up before i take it in.

how much are they, from fords or motor factors? seen one on ebay for 8 quid plus postage is this good, or should i go to fords to get one, as i get a 20% discount.

advice please

its for a S2

p.s. anyone know why my reverse lights arent working, bulbs are fine, have a b and m kit, cant find the reverse switch sensor, whats it look like?