From personal experience their "used-like new" status from Amazon warehouse is usually "like new" - item itself might never have been used except for being opened (sometimes not even opened - I'm returning a keyboard without opening it since I got the upgraded version after it fell in price on Amazon).
I know that it is already 2 generations old by now - but if you don't see much benefit from the extra features of a MX 2s or 3 then the original MX is one of the best mice you can use in my opinion. At this price I got one for office use instead of the standard Dell mouse they give everyone.
When it first came out years ago it was £80 - now down to £29.36 for UK buyers and around £30.10 for Irish buyers. Camelcamelcamel did track it as falling to this price new every so often too but currently it's back up at £48-49.