Take some time and get familiar with the current bike you have (your cousins?). Learn how to tune it up, and get the shifters working (spend time, not much $). Ride it for a bit (provided it fits ok), relax-take it easy. When you get familiar with the basics, and you would like to change to a newer-or different style of bike, you'll find it easier to figure out what's a "good" buy vs what's not.