This, while seemingly a natural extension, is a bad idea, imho. Investing in startups is inherently one of the riskiest investments you can make, and having deals be public is a problem, as 'normal' investors will be swayed by charismatic founders into losing their homes.

That said, 'auctions' for accredited investors already exist, if the company choose to take advantage of it. There are seed funding sites as well as AngelList, etc., to publicize deals.

Some founders also choose not to publicize a raise (except among the VC/angel networks) so as to remain under the radar until they are ready to launch.