Big B's are good horns, but that one looks like it would be toward the bottom end of the Big B price range.  Condition is everything.  The neck doesn't look like an original Big B neck.  The replacement may or may not have worked out well.  There's also a flat spot on the left side of the bell rim.  A whack like that can cause alignment problems on the bell keys.  To find out about those issues would take a thorough inspection and play test.  At the very least, figure in the cost of a good overhaul.  You can get an idea of sale prices by watching closing prices for Big B's on eBay.