british hardwoods are 27 for 1" and 30 for 2".
It seems a bit steep, but you have the ebay/conveniece factor which sometimes increases prices. Wide boards are a premium, although debatable whether at a minimum 10" it is a wide board. I forget how it is measured, or should be- isnt it at minimum width?
probably a bit steep, but it costs nothing much to advertise it, so seller is probably giving it a try.
buying in small quantities- a board or two- the seller can charge what they like. We/you are not attractive business to the timber yards (apologies if you buy 10 cube at a time, I dont)
On the other hand, it is quite cheap. You buy a board for 50 quid, make something from it which takes you 20hours, enjoy looking at it for years, pass it to the kids etc. Suddenly the "cost" of £50 sounds like peanuts