Hey...I started flying when I was your age. I own a 152 and am also a CFI. Feel free to email me if you have questions as you go along. Hopefully you and your CFI aren't too big. My airplane, with full fuel, can only take two 160 pounders and still be legal. The 152 is a great little machine as long as you understand its limitations....doubt you could find a cheaper plane to train in....heck, you should just buy one.
Good luck! Yeah, the 152 is a fun little plane...just make sure you're instructor and you aren't both overweight! That can be dangerous... but the 152 is a cute little plane and great to train in. •, just buy decent one for $18k as soon as you can afford it (after you've gotten out of college though and have a good job!)