I believe it works like this:
If someone makes an offer of say, 160k gold, and your offer is 100k, the offer would then be just one gold over that and it would continue up until the 160k limit. The offer that shows up is only as much as is needed to beat the other buyers. So you just need to make a high bid, however much it is that you're willing to spend as a maximum, and hope that nobody else has set a higher maximum bid.
