Are you talking new or used? Stainless/synthetic or wood? Which model?
I can tell you that most wood/blue versions of the 84M are in the $750 range or so. Stainless synthetic are in the $900 range or so.
I recently bought an 8400 (the WSM version of the 84) for about $850. It's on order and should be coming within the next couple of months or so.
Zachary