Hit up Ebay and look for Wallbike. They sell returned saddles and you can usually get them for about 65% of a new one. Of if you aren't sure you want one, you can order a new one from Wallbike and they have a no questions asked 6 month return policy. In the case of the bike you are describing the B-66/67 would be the best choice. The B66 is double rail for a straight post and clamp the B67 is for modern single rail micro adjust posts.

Aaron