Shadowfang is only worth what someone is willing to pay for it.
Example: Let's say I run into someone who has 2 shadowfangs for sale. He's put them on Ebay, put them on the forums, and they sit there not selling. I show up with my 1k gold and offer him 500g ea. He says 'fuck no! These babies are worth AT LEAST 25k each!' so I point out that there is no one lining up to make offers. At that point he has to realize that as long as there is no one making an offer, his shadowfangs are worth nothing. If enough time passes, he will realize that my offer was probably the best offer he's going to get.
1k for 2x shadowfangs is more than reasonable given the circumstances. Paying real life money to xfer characters with enough gold around, then to xfer the shadowfangs back to the character you want it on, gets pretty ridiculous.