Try ebay. they are discontinued and one of those lenses that have a big following.As far as my preference goes, all I can say is "Canon 200mm F/1.8 USM".
For quick action on a field, rock climbers trying a difficult rock face or free ride mountain bikers, I only have to reach for this lens to capture the action.
Where can I find one of those so I can be sufficiently sticker shocked?
I went to Ebay and saw one for $3000... that wasn't outrageous...