fiestaware gray teapot or tea pitcher

I have my eye on this gray fiestaware teapot in a local antique shop. It is not the same color as the item pictured here but it is the same teapot/tea pictcher in a gray. Can anyone tell me what it may be worth paying for, when this teapot was made and by whom? Is it fiestaware or is it a fake?

I would expect to see a stamp at the bottom of the pot as you can see in this picture http://www.indiana.edu/~e472/cdf/suggest/old/FiestaWare.jpg
If the pot you're interested to buy has the stamp you'll have to trust that it is authentic.
As for the prices you'll have a very good idea if you'll check the eBay offers http://collectibles.search.ebay.com/Fiesta-Ware- Heather-Mini-Disk-Pitcher-Fiestaware- Second_Collectibles_W0QQfsiZ1QQsacatZ1ho
Hope you'll buy the pot at a reasonable price that from what I've seen is up to 25$

It is priced at $500.00 dollars, I am trying to figure out why...

Thank you for telling me about the stamp!

I haven't seen anywhere a fiestaware teapot at more than a hundred.
I would check with them what makes it so unique