I feel the struggle. I too am in college with a lot of friends birthdays coming up. 9/10 I let them know I have thought of what to get them but let them know that money is tight and say it might be late. And then i go out and buy kids cards, especially ones with like the numbers on them and just add on to it, so like say i have a friend turning 23, I'd get them either a card for a 2 year old and draw a three on there or a card for a 3 year old and tack a two to the front. Double the point if it comes with a cheep sticker, coloring pages, a plastic key chain, or deconstruct the card to make something out of the card. So far this method hasn't failed and has given plenty of laughs and impromptu phone calls when it arrives in the mail!