How about the rag-tied flip-flops. You cut fabric into 6 in. X 1/2 in. strips and tie them onto the flip-flops across the toes. Wal-Mart has flip-flops and I think they are about $2/pair. Their fabric solids is usually under $2/yd. and it takes less than 1/3 a yard per pair. You can use the team's colors.
Since they are small kids with small shoe sizes, they won't take too long. (I made 24 pairs for a cheer camp one year, but they were older with bigger sizes.) If you cut a bunch of strips and then put on a movie while you work, it doesn't seem to take too long.
Good luck! :o)