My estimate was about $12K Aussie over three years for my PPL - took me close to 80 hours; I did it slowly.
Have to agree with the above posters re. flying with others. You learn to fly how your instructor flies - you see what really happens 'out in the real world' with other guys - and hopefully you find your own way to operate, striking a happy medium. Great once you have the PPL as well - with pilots both more experienced and of similar levels.
If nothing else, it's a good excuse to go flying!