Gumtree
I know it may be an obvious suggestion, but I have seen quite a few Kirby's near me on Gumtree, apparently, quite heavy for most people.
Also, try posting advert's in the 'Wanted" section of Gumtree, saying that you want a Kirby.
Also, don't forget eBay, set up a Watch for them so they don't slip you by.
Good luck on finding one Tayyab!