I know our Dollar Store has huge inflatable inner tubes in bright, neon colors. At our end of year pool party one year, the moms bought one for each of the kiddos in the class and wrote their names on them (in a really cute handwriting) with a black Sharpie. That way they all had something to play with in the pool and had something nice to take home as a favor.
At a dollar each, how inexpensive it is would depend upon how many little angels you are inviting.