Sleigh Builder 995 diamonds?
I put 2 back into inventory as I didn't find them very useful, so it's obvious they are putting up things that where won during past events so maybe they will be of use to newbies who want these buildings to add a bit of glamour.
I think inno are mostly trying to cater for fresh players in this sale offering items from previous events, and if youy think about it, someone just starting out who is sitting in early middle ages would see value in these items, obviously not everyone is on a budget and spending diamonds in early stages of the game does give a boost. But I would be waiting for actual events where these type of buildings become prizes, it's much more satisfying to of won special buildings, even if you spent diamonds rather than buying straight out.
It kinds devalues the effort players put into winning things when after a while others can just buy there way in.
I reckon once inno deem this game non viable you'll be able to buy anything, a level 80 ark, 50,000 diamonds