I would defenetly suggest a crested gecko! They dont need a big tank (mine is 40*40*60 and you can go even smaller for one animal), they are small, very cool, and the best part THEY DONT EAT LIVE FOOD. Your geckos staple diet can be repashy cgd with a small adition of frut and insects as a treat. I vote for a crested gecko!

I know exactly how you feel. With school and other responsibilities having so much pets is a big time consumer and you have to give them good care because if you dont they will die.