Lots of luck on finding them.
If you want something not bad while you are looking, I used a set of cheap hoods from the LBS. I think they are intended for Weinmann levers. They are cheap though, hard plastic. Local guy charges me $6 for them.
The Shimano levers are surprisingly square, I pushed a piece of cork handlebar tape up the back to fill in the square shape. I think if I was to do it again I would try taping the handlebar tape in place before putting the hood on.
