WELLLLLL
I suppose George can ask the price that he wants for it...the machine seems to be very well kept and decals on the bakelite hood are still great !
In the UK HOOVER SENIORS 652 ( your USA 65 CONVERTIBLE model ) can easily be sold for 100 to 200 pounds but sometimes go unsold for 10 pounds. So it depends from the market and from the moment; sometimes there are 6 of them for sale at the same time, and sometimes you don't find one for months.
It would be a great start for someone starting a vacuum cleaner collection, for example.
As far as shipping carton, attachment set & caddy, instruction manual....this is only an obsession ....these are absolutely not necessary items; If you don't have them it does not mean your cleaner is uncomplete ! They are only (recently)appreciated "extras" - which were often sold separetely - but unnecessary for the machine value. The machine itself is important, with its unique design, personal history, technical "new" features and improvements, materials, etc
Moreover, speaking of such vintage machines I think there is no pre-estabilished-market-price for such items, as each of them is in different conditions and is a different case. If the price is high for you, just don't buy it and keep looking for old ladies who will sell you their lifetime vacuum for 15 bucks !
The real luck is to find a machine which has not been "restored" yet by some unexperienced ( but also experienced ) collector because that's the best way to lower its value. That's the reason why I usually try not to buy from other collectors. These are of course personal opinions.
Paying 40 dollars for this vacuum cleaner is quite an insult to the machine itself and to anyone who collects vacuum cleaners. For getting such a ridiculous amount, I would better keep it and wait for someone who can understand its value.
Cheers !