A sealed bid is generaly used in the uk in the property market the vendor, the agent and the bidder are the only ones who should know of the offer/offers the property is offered in this way for a set time ie all offers should be recived by the agent by 12 noon on the 14/8/12
used it a few times in the property market i do think its open to abuse for various reasons and cant see it being used in this enviroment.
Much like contract work - contractor places a 'price' bid to the company needing work done?