I own 2 Billboards. First is JRD778X which dates October 2003. Second is JRE845x. The first year (JRD prefix) are the ones that are rumored to be assembled by the Performance center crew but rumored to only be in the first 1000 of the serial number run. After that, and the second year (prefix JRE) were done by the normal line.
If it is NIB (with matching box and everything) for a second year, I'd put it at $700-$900 depending how badly I wanted one. If it was in the first 1000 produced, I would say $1000-$1200.