I can tell you right now.....
The fairly current 2015 issue of Kovels Antique and collectible guide, only has one listing for a early pre, non electric pump vacuum cleaner valued at $50.00 and change. Take into consideration that there is not really a world wide demanding market for vintage vacuum cleaners, like there is for vintage Barbie dolls for instance, where something high dollar has a chance of selling for a high price. Now also taking into consideration that this Westinghouse canister is about 60 years newer than the said pump vacuum cleaner in the mentioned price guide.
Also a big factor for us collectors is completeness. You only have the canister unit its self pictured. Do you have the hose and attachment kit? What kind of condition are those in? Is the attachment kit complete, and do all the attachments seem to match one another?? If it is just the canister only, that is major points off for value, versus a complete set.
So I would then do as ElectroluxXXX said, and list it for 99cents and be happy with what you get. Good Luck!
