R22 PPL:
65 hours x £400 per hour = £26,000 ...+ six hour R44 rating (at £600 per hour) £3,600 = £29,600
(but...will you get the R44 rating in just 6 hours?, and how comfortable in it will you be for taking pax?)
R44 PPL:
60 hours x £600 per hour = £36,000
(R44 is a bit easier to fly hence you get your PPL in fewer hours)