Prices of rares are most often based on the desire amongst collectors to collect them. If you are looking to perk up interest of people in your item you should put some extra effort in it then simply saying, "I have this item."
There are dozens of related questions that you can easily answer to help others to help you:
1) Where did you get this item?
2) If it was from an event, how about telling us a little bit of that event to paint a picture.
3) If you bought it from someone then what did you pay for it back then? And who was it?
4) What shard is it on currently?
There is no master catalog with prices of every rares. If there is one then it is most likely inaccurate. It often depends on the fancies of the seller and the buyer. All I can tell you based on what little you have said is that they were going for 30M gold when they were given out according to the event items sticky. However, it is probably worth a bit more now. Hope that helps.
Cheers.