I keep receiving e-mails from Prudent Press Agency too. In fact, I just got one today (August 25, 2004). Except that in the e-mails they send me, they say their prices start at $200.
My instinct would be to stay away from Prudent Press Agency. If they're so desperate for business that they have to send unsolicited e-mail to addresses they have harvested off the Internet in some way, then I question their effectiveness in placing press releases where they will do the most good.