Why are prices higher than what I bid?

When this happens, it's because your bid prices were not accepted. 

When an offer is rejected, it is updated to the list price in your cart.  The cart is divided into separate sections – Accepted, Rejected, Countered, and Awaiting Review.  If you check out with product that has Accepted offers, as well as product that has Rejected offers, the Rejected offers will reflect list pricing.

You can choose to checkout product with Accepted offers only, and this would match the offer price you expect to see.