If you're doing this because it seems like an auction, it is not.
There are two defining characteristics of auctions that this lacks. Using ebay as a comparision because it is the major auction site
1: If there is a BIN in an auction, then the BIN is cancelled when the first bid is placed. This is not. Offers can be thrown at any time, and anybody can pay the BIN when they want.
2: Auctions can be sniped. Sniping is not possible, because there is no set in stone millisecond to submit an offer. I have a end date only because I will be leaving on a trip soon and want to set a date so the offers come in faster. However, at any arbitrary time on Wednesday, I will see who's offer is best and take it. Its unsnipable.
What this is similar to:
Ebay BIN with best offer.
Why? Ebay BIN with best offer allows anybody at any point to pay the BIN. However, anybody can submit a offer before that. The only difference is I publicly display the offers, which ebay does not. However, ebay has a system where you can auto reject offers under a certain amount. You can edit that amount at any time. GH does not have that, thereby showing the current offer I have artificially created a lower bound of offers to auto reject.
If you still don't like it, let me know, and I will remove the public current best offers. I do not believe I have remotely wronged any other rule in the classifieds rules.