After the agony of negotiation in Tanzanite Internation in Cozumel, I purchased a loose 4kt tanzanite for $2,000. When I returned to the states it appraised for around $2,900. From my memory, I think they originally wanted about $3,500 for it and I worked them down. This was in 2001, so I am not sure how it compares to todays pricing and value.
Overall, it was a miserable buying experience, but I was pleased with the final outcome.