Apparently, it's collector quality and has provenance. BE's in themselves are not common so I wouldn't be surprised to see it sell for as much as a CE grade in comparable condition.
Since it's a collector's item as opposed to a commodity item ( you can't readily compare it to another example across town) only a high profile auction would set the market value.
OTOH, if you're shopping smart in order to recover most of your outlay or make a profit on resale, I'd say $3-4K-ish wouldn't be unreasonable....provide it really has no issues.
Just one man's opinion; a man with virtually zero experience in the collector market.
