We have a market and investors decide themselves what orders they fill and when.

So if you look at the market and sort by price, you are on page 3: https://www.minnowbooster.net/market?direction=asc&page=3&sort=effective_price so there are roughly 50 other users who want to pay more than you to get steem power. It the current moment there is a huge demand for steem power and the prices reflect that.