okodoka-
As has been said, just look into rifle scopes!
Who ever told you that they won't work apparently isn't very knowlegable about scopes OR crossbows!
I understand not everyone likes red dot sights. Everyone's different.....different people have different desires...that's why there are many scopes and sights to choose from out there. Just go to Cabela's or other stores web site and look around till you see something you think you'll like.
Here's a place to spend a coupla hours...
http://www.opticsplanet.net/riflescopes.html
Mike