I learnt solely with my dad, with the exception of one lesson on my 17th birthday to go over basic clutch control.
Although I passed first time (drove my own car in the test which was a bonus), I'd be cautious about recommending it to others. & it completely depends upon your relationship. Are either of you likely to lose your cool?
Edit: In terms of cost, for me..
Car ~Β£1300
Insurance Β£800 provisional insurance (car was in my name so insurance had to be in my name as well, ie couldn't be a named driver). That was for a year though and when I passed we just upgraded it to full licence insurance (think it was Β£1200 for the year, minus what we had already paid for the provisional insurance). This was particularly handy because I got my car insured on my 17th birthday and had my first year no claims on my 18th birthday.
Petrol depended upon how much driving we were doing. A tank for my car costs about Β£45 and it would last a few weeks.