It's a fantastic book and whilst it's out of print, it's not that rare. I've seen copies on ebay for <£100. I have seen that one on Amazon, it's been there for a long time because it's a stupid price.
I wouldn't worry about insuring it. It's highly unlikely to be worth more than £100.
nah that price is really daft, last year there was a seller selling them for £30-£50 (can't remember exactly) english version...I remember as I was going to buy one but bought a disney tradition ornament instead!lol..thats the book with the blue sky and castle on the front eh? oh and 100% thats was on amazon!
I suppose you have to give the seller 10 out of 10 for trying but that is a stupid price hence why no one's snapping it up.
It's such a beautiful book, my DH gave me a signed copy for Christmas after our first couple of visits, then we bought a signed copy for our eldest DD as a present for doing well in her GCSEs.
As for insurance, it should be already covered under your general household contents insurance and I think it's a very very long way off from needing to be insured separately but it wouldn't hurt to take a couple of photos to prove which edition you had just in case anything every happened to it.
I wanted another Disney book that was long out of print - second-hand copies were for sale on ebay and Amazon for equally ridiculous prices too (not selling, mind ) but I was patient and after about a year I found a brand-new copy in a bookstore in mid west America and it cost less than £40 including shipping so if anyone is wanting to find Sketch to Reality bide your time and you may be lucky to find it at a realistic price.