Buy at the markey place

where is the market place on Midnight castle??

xor, sorry, there is no market place in Midnight Castle. Please let us know what you need so we may be able to help you

it could be in Cloud City, but I don't think you can 'buy' anything there.......

It could be that they are wondering where to buy diamonds and coins.

yes, tazruby, that was my guessing, too, but the question was not really clear

you can only buy coins and diamonds through the game. There should be a button beside your coin and diamond tally in the top right of your game.

To the original poster: In case you meant the Market Master-achievement, there's no specific market in MC for buying items as has been previously posted. You'll get purchases toward that achievement every time you buy items with diamonds in their respective scenes, for example, if you go to a Zoom Zone, like the chest in Rock Garden, and instead of having the key you can find in HO-scenes, you pay 3 diamonds to open it, that counts as a purchase. Also buying ingredients for crafting count towards as purchases.

For more info on what counts and what does not: Look for the locked Helpful Links-thread on this forum. In that thread, there's a link to Midnight Castle Strategy guide that has a treasury of info about the game, including info on some of the less clear achievements.

Or, as Gernespieler kindly asked, you can clarify your question a bit further so we could help you better.