It is however the buyer wants to buy it at.
Let x be greater than y.
If person A wants to sell it at x rate than y rate, let them buy them at x rate. However, if person B wants to and try to lower the rate to y, it will be least likely because person A is selling at a higher price and users will be attracted to x rate.
The best option, from what I heard in other threads, is to not buy. They will either simply lower the rate or just raise the rate even higher. We control the rates/economy.
I hope this post is clear enough.