Each prospective buyer has a responsibility for posting their offers to the seller. The potential buyer assumes responsibility that the seller acknowledges and understands the offer. No purchaser or buyer should be forced to assume if or who the other buyers might be. A potential purchaser cannot assume that a transaction has not or will not occur without their input unless the seller has explicitly agreed to and stated this fact. In other words, the first "I'll take it" takes precedence unless otherwise agreed.

In any transaction you may only get one bid/offer. Don't assume you're the only bidder/buyer. Don't assume that you control the pace of the sale. Don't assume that your negotiation takes precedence. Don't assume that unacknowledged communication actually happened.