Should I just buy the cellphone charger?

i really don't want to waste my $ but... I lost my cellphone charger and its my fault because I didn't put it in my bedroom when I should of. Anyways, I have a summer math class at my college starting this week on Thursday. My dad says he got 3 weeks off where he can drop me off and pick me up, so i don't have to buy metro card rides. This wouldn't be good if my cell wasn't charged because what if I decided to hangout with friends after class ( class starts 9am ends 12:30pm)? Should I just suck it up and buy one? I have been using my moms cellphone charger that only works in the car..