To give an alternative, the school I fly out of charges 235 quid/hr dual or 170/hr SFH for a R22. I'm not saying that the R22 is better or worse than a 300, as I've only ever flown a 22, and thus am not in a position to make comparisons.
I have an idea a R22 costs around 120 pounds per hour to run, although that would depend on insurance costs and how much flying you actually do in a given year.
Cheerio
P'let