was it just me or was this site crappin out a moment ago... I couln't load a page for my life...
anyhoo:
Thorntangle-  
Come on people - it's a Bulette! It's not sheep or pig or even crocodile. It's a rare, vicious predator that swims under the ground and has super tough skin. That hide gives it a +12 natural armor bonus! A set of Bulette hide armor has got to have some style points too. Would it help if we made a matching Bulette-hide wide-brimmed hat to accesorize? 
 
if you have a MM handy, check out the rules for making dragon armor- no matter how skilled you are, and how huge the dragon was, all you can do is make MW hide armor.  No nat armor bonuses, no nothing.
If you really want a cool hide armor to sell, have the cleric (if he can be resurrected) or hire someone with the craft arms and armor feat (should cost a pretty penny tho) to enchant it with bull str and bull rush.  Then you have a beefed up rhino hide armor which will do very well in the open market.  
A bullete is no more exotic than any other creature in the MM.  It is as rare as teh DM wants it to be.  If he decided tomorrow that there is a festival where they run through the city and the townspeople run with them (the annual running of the bulletttes) then hell, I would say that bullette hide armor is a pretty common thing.  
But as is, you should be happy that your DM is considering giving you the chance to make armor from this guy- just from the rules, you can only make hide armor. Dragon's hide is the only thing that is strong enough to make heavier armor (plate and mail)