What would be a reasonable price to sell/buy a second-hand cello?

[frogs]

Ds has outgrown his 1/4 size cello. It is a chinese one, but a good one (chosen by his cello teacher). In immaculate condition. We paid £300 new and I was thinking in terms of asking £200 second hand --does this seem reasonable?

By the same token I was planning to buy the exact equivalent cello in 1/2 size from a friend of dd1's, so want to offer a price that is fair to her and fair to us.

TIA

Any cellists around, or parents of little cellists?

dd plays the cello and she's on her 3rd now. We go to a shop where they buy them back half price. We bought a 1/2 size a few months ago for around £450 (chinese one). We must have sold them the 1/4 size for around £225 (sorry for vagueness....).