The following company is now selling 50mm Hitch Balls for $19.95 plus
shipping. You can order via their web site. I am not affiliated with them,
but I did just buy a hitch ball from them.

The Hitch Corner
10677 W. Centennial Rd. #103
Littleton, CO 80127
Metro Denver Area - 303-904-1558
Toll Free - 1-877-66HITCH (664-4824)
Hours: M-F 8-5 (MST)
Sat 8-12 noon (MST)
www.hitchcorner.com

John Scott