If you have the time:
Flight to LA: £350
Hotel for 6 weeks: £1000
50 hours PPL package (all in): £4,051
(example taken from one well known outfit which includes everything you need, including ground exam, medical and flight test fee)
Total: £5,401 for everything......guaranteed not nuch weather standby time.
In the UK:
50 hour PPL course £6,500 including ground exams for a similar aeroplane
Landing fees ~£250
Club membership (?) £?
In reality not many people complete a PPL in under 50 hours.
Not knocking learning in the UK. However, the USA IS cheaper, and if you have the time can be a brilliant holiday. You may even learn to lean properly if you go to the west coast