I'm sure this has been covered, but I searched and couldn't find anything so...

I'm 22, in school, and have a part time job. I am interested in getting my private pilot certificate because i've always wanted to fly, and I plan on being an engineer in the aerospace industry once I get out of school.

I would really like to go ahead and start flying, but money is an issue. My question is, what is the minimum amount of flying I would have to do per month to make progress, and what would be an estimate of the expense (plane rental, fuel, instructor, ect).

Please base your answer on the best case scenario because I do well in school, and I like to think I have good "feel" for this type of thing.

Again, sorry if this has been covered already, and thanks in advance for any responses.