Chilhowee sells theirs for $85 plain. Studs, pockets, etc add to the price. I think you need to offer one without the pocket as well. Here is a link to their site:
http://www.chilhowee.net/suzuki-tankbra/TB047.html How does yours attach? Could you include photos of the top and bottom attachment points?
To answer your question, I think you are in the right price range. Maybe. The Savage one is expensive because there is no supply. If you look at the offerings for the "popular" bikes from other vendors, most are in the $50-$60 range. Many are even less. Personally, I think to sell well you may need to be at the lower end of the price range you gave for one with a pocket and less for one without. But I'm a cheapskate when it comes to this type of stuff.
And I would offer a matching fender bib as well. When we go to solo seats, the fender is ugly and I think the fender bib and tank bib would need to match. While you're at it, a matching tool/fork bag would be awesome too!