scooby(puppy power)

coming home on motorway put it in 5th gear just as i got past 4000rpm the car jumped and the engine light came on(checked it with a cheap obd2 code reader i bought from ebay), an it came up with fault p1245 which according to the manual is the fault above, reset the fault went out in the car ok in 1st to 4th soon as in 5th did it again, i take it the wastegate solenoid is the boost solenoid and this is whats on its way out if not already gone, where is the best place to get one and how much are they,

ive already checked all the pipes and they seem fine.
cheers