What this means as a buyer is: always check to make sure the Buy Box is the best price option.
What this means as a seller is that you do not have to be the lowest price FBA seller to get the Buy Box. I usually try to price with the pack but never specifically look to match the lowest price.
Example: A toy has a rank of 1000 and their are 10 sellers each having 10 units let's say. The lowest seller is at $14.99 the next three are at $16.99 and the others are $19.99. Given this scenario I would price at $16.99 and the price up as they sold. You can always drop your price but you can't get the extra money back when the item sells for lower than you could have gotten had you not matched the lowest price.
I find this information to be very useful when buying and selling in Amazon at this time of year:)