I think you are wrong about the bidding information.
The 100% refers only to the bids which the bidder has on auctions in the last 30 days, not all the bids the bidder has ever made.
So just because that bidder has only bid on one item in the last 30 days, that means it is a shill bidding account?
Having said that, the final price is insane. I paid £368 for my a500 back in the day (Computer Exchange, Princes Avenue, Hull) - I couldn't afford an external floppy drive at £50, couldn't afford a monitor (around £200), and had to save for ages for the cheapest half-meg & RTC upgrade (around £50).
Sigh, happy days...