I made the one on my Ultimate from a Dubro heavy duty servo horn and two mixing arm bearings from a model helicopter. I have used the Nelson offerings, and they were excellent. I just had to wait three weeks to get the one I wanted.

If you're doing a big model, I would spend the bucks and get a Nelson. If you're dealing with a 120 or so size model, making one out of available material is fun and educational.

If you're interested, I can post a photo of my homemade one when I get home this evening.