£250 to £350 for a a decent vvc cylinder head pressure tested and skimmed,hot tested & vvc mech timed up.£40 loom,£50 ecu with lucas box and fob,decent head gasket stretch bolts pretensioner timing belt,water pump.oil and filter prices vary on ebay.i would estimate no more than £500 for the parts.A decent mechanic would take 4 to 6 hours to swap the heads over there fees i cannot speak for,a lot quicker and cheaper labour rates than dropping subrame and swapping engine,gearbox over if you not looking to do it yourself.