Depends on the 1 million account you're buying retweets from. I've seen a lot of million follower pages on twitter and most of them are dead. I would suggest you watch the page you plan on buy retweets from and see how organic it is with its retweets and favorites in first hour or so.
Do you have the cash to keep buying RTs? It's going to add up quick. And have you figured out a monetization plan after you hit your 100k mark?
Purchased retweets are tough because the kind of accounts selling retweets are typically the kind of accounts that have a less organic and more bot populated followers list.