My Dad has an asparagus special. In the past several years i have only seen a handful that actually look like the picture in the Allis Chalmers Historical book. We have found some differences though. Some had 38" rear wheels and some had "36" rear wheels. Also the fenders might be regular b fenders or we have seen one that had fenders like a WC.
There was one for sale in Iowa for 3500.00. Beyond that I can't really give you a what its worth figure.