A vintage 8" Bahco 51 wrench sold on Swedish EBay (Aug 2015) for a record price of 2027SEK (equivalent to $322 AUD).
This model is called a generation 2 wrench (1911-1913) and is the most collectable of all the Bahco, with the next most expensive Bahco probably being a large 12" Shark wrench No 23, or a 12" double header 73/72 at about the same value around $200. Put that in perspective, when an ordinary 8" Generation 3 would fetch no more than $20.
There seem to be just a few collectors worldwide interested in collecting Bahco, with the same names coming up over and over on auction sites. Previously another generation 2 Bahco 52 sold for 1500SEK ($238) and that was considered high. These prices show that when you get just a couple of keen bidders the price of collectables quickly enters bubble territory - just like Sydney Real Estate! In this case the prize was won by a Finnish collector known to have quite a sizeable collection, including at least 4 Generation 2 Bahcos. Price may not be an issue to the collector however, as he probably doesnt intend to ever sell it. If he did, it would unlikely ever see these values again, or at least until collecting Bahco becomes more of a mainstream activity.