Good deal or not, without knowing how much shipping added to the OP's cost, it is impossible to know if the deal was good or not. Twenty plus dollars for a nice TTT stem is not at all unreasonable, but if it cost $25.00 to get it from the seller to the buyer, my answer would be a bit different. Also...

If that is the exact steering stem the OP wanted, then most prices would be justified. If, however, he or she just wanted a steering stem, then my guess is one could have been found or considerably less.

I sell standard stems for ten bucks, locally. But if you want me to go to the trouble of answering emails, posting pictures on Ebay, packing and then shipping the item, be prepared to cover my handling costs.

This might sound commercial to some people, but my time is precious to me. And it takes time to do all of the above, not to mention finding the steering stem, in the first place.