Gather you not into Kirbys Paul?
Lets be helpful.
If you go onto Ebay there are a few G6's for sale, obviously auction running so the bids are still on the up. Someone started bidding at £200 but got no bids yet, another with buy it now price of £250.
G4's (slightly older) in good nick go for about £150-£225
Start low (£100) and work up.
Has it been serviced regularly by Kirby or an agent?
Guy on Ebay services Kirby for £65 exc parts. You get it to him but the £65 includes return post which can be £20-£25. Gives it a good polish as well so it will look good.
You can get the bits off Ebay, bags are cheap, Google Kirby and you will see there is a Kirby club with some useful tips.
From G4 onward I know they had the TechDrive power assist so moving it was made a lot easier.
For the bigger jobs I would like a Kirby. Too heavy, IMO, for every day jobs in a "normal" domestic. Certainly move the pile about.