Well, as my great-grandfather was known to have said regarding horses, it's worth whatever someone will pay for it.
Vacuums are such a niche collectible, it's hard to put an accurate value on them. What is a treasure to one person is worthless junk to another, and everybody on eBay thinks they've got an incredible treasure to sell and they want ten times what any rational person will pay for it. Meanwhile, thrift store prices are just all over the place with absolutely no rhyme or reason. As the manager of one told me a few months ago, it all depends on who has the price gun in their hand when the item comes in.