Most expensive adult tarantulas?

[zeusophobia]

Just wondering about price on adult tarantulas. I'm familiar with some popular ones, but a friend told me rare and slow growing tarantulas can be over $500 as adults. I'm just curious about this because I've never seen anything over $300 and I've been to repticon.

 

[BrokenRay]

Right now on a popular dealer's site sits a Xenesthsis sp blue 1 1/2 to 2 female at $450.00