Alex,
I know the sums seem daunting, and the truth is people who are promoting their flying [instruction] service will always quote you minimums. You must plan to spend more than just the minimum to learn to fly, as very simply there is too much to learn to do it adequately in the minimums. To be honest, I could not see how it could be properly covered in twice the time. Good on instructors who succeed in preparing their students in the allotted time!
The next thing is to consider what you will do with the "ink is still wet" license when you get it. Unless you're just getting your license to say you did, and never flying again, you have more renting to do. Yes, solo, it'll be a little less, but not much less. So, you better plan to have an appropriate budget to continue flying after you complete your training. Don't start, 'till you can continue...
Your best way to economize training costs, is to be very thoroughly prepared for all of your lessons, with background knowledge. There are hundreds of great books (the Flight Test thread here list s few specific ones). Dedicate yourself to those, and you'll get the very most, in the least time in your training. Luck (and brevity) in any training favour the prepared...
Good luck!