If you want to keep his top knot hair long, you can either buy bands in boy colors or buy boy bows for those special occasions. Or you can just cut it.
And here is a link to a lady who makes all kinds of bows:
http://stores.ebay.com/Vals-Diva-Dos
She can do whatever kind of bow you want. You can probably email her and ask if you can buy some of the pony tail elastic bands as well.