Belmont beauty salon chairs are still in production today, not many collectors for items such as these but designers like them & people do buy them as curio pieces.
What are they worth ? what ever you can get for them ! No good on ebay as postage is difficult so buyer has to collect,
local paper ad or fair/carboot, ask £200 ( £40 a chair) & be prepared to go down to £15 - £20 a chair
General sale auction no reseve would be my favoured route of disposal, they will find their level. They cost you nothing , whatever they make is a bonus