To buy 200 bitcoins it means you will have to spend around 1.2million$ Based on the current bitcoin price ,you can take your $1.2m+ and visit one of any number of exchanges to purchase your BTC a few at a time. I’m not aware of anywhere you can make an instant purchase of that size without going through extensive AML/KYC processes and/or waiting an extended period of time.

Your best bet here is to get an account on each of the P2P exchanges and buy a few coins at a time, making a few transactions each day, over the next week or so through various trades. You’re going to pay above current market value no matter where you go. But, this will allow you to make the purchase you want to make in the least amount of time with the least amount of hassle.