So as in title, Is it possible to buy really large BTC amounts? like a million $? What was the largest amount of BTC you bought at once?
Yes Bro You can Buy Large Amount Of Bitcoins From Many Exchanges Like Localbitcoins, Coinbase, Poloniex etc....
But I suggest You to Dont Buy Collectively, Only Buy Bitcoins From Different Sites Because It is More Safe and always Put Different Btc Address On Different Exchanges...