Well, if you live with your parents, Im sure they can buy you another, and the feeding it wont be any less you still get huge bags of food, and water comes out the taps :D
If you live in a student flat or your own, Ask your parents to lend money, if not why not just buy another one, its not much for a piggy, And also i strongly recommend toys, they keep a guinea pig entertained for a while, You can make your own little toys and so on, make his bed more comfy, feed him alot of fruit and veg, If its a female, getting a male will be great! they might make love and so on Lol, but if its a male itself and getting a male Might cause fights "Such as territory grounds" and food, But they normaly dont fight, so it should be fine. Also it the guinea pig has any metal bars he can walk on, cover it with carpeting or somthing softer, they dont like it much.
Hope this helped, You can always get a job as a paper girl, Or work in a chinese shop or chip shop, I hear you get days off if you got a job, work experiance or somthing.