no worries
if about £250 (inc postage) is the going rate, that's not really unreasonable..
see here
or here
obviously you'd check with them first with your VIN and probably try and find out what the mileage was on the donor car if possible..
of course the real cost will be paying someone to swap it for you.. anyone know the going rate for a gearbox swap?
does it feel like you've got any unexpected slack on the gearstick when you wobble the lever about? I've heard of people replacing bushings in the actual level mechanism (under the centre console) in other types of cars when the werent getting into gear properly.. am no expert on Volvo in particular mind you