Scotch By Nino Marchetti / October 5, 2015 The ever hot world of collectible Scotch is getting set to turn up the heat again this week in Edinburgh, Scotland, where old school auction house Bonhams will be having a rare whiskies auction. It is expected, by the time the gavel is done falling on October 7, that at least several bottlings will fetch a pretty penny or two for their previous owners.Sitting at the top of the heap for this upcoming auction is the Glenfiddich 50 Year Old. This Scotch, currently ranked the third most expensive whisky available at retail according to a list maintained by Wine-Searcher, has an average street price of close to $22,000. This number, near to the top end of what Bonhams expects someone will pay for it, is a significant jump from five years ago, when its average retail price was around $12,500.For those unfamiliar with this bottling, Bonhams said it was bottled in 1991 after having been drawn from a batch of nine casks laid down back in the 1930s by the Grant family, who runs Glenfiddich. Only 500 bottles of it were released.“This is one of the most desirable Glenfiddichs – or, indeed of any Scotch whisky – and is keenly sought after by collectors for its exceptional quality and rarity,” said Bonhams whisky specialist, Martin Green, in a statement.Other interesting auction whiskies coming up for sale include a Bowmore Premier over 42 years old that was distilled in 1965 and bottled in 2008 (expected to fetch up to around $9,100); a Dalmore 50 year old (around $7,600); a 1929 Glenlivet (around $3,000) and two bottles of The Macallan Select Reserve 52 year old (around $9,100).