According to Game Informer, your likely better off on average just buying select games from PSN or retail stores than renting them using the upcoming Playstation Now service based on the beta.
In an email sent, Sony deflected blame for the pricing saying it was left entirely in the hands of developers and publishers.
GI's chart comparing around half the games available shows the 4 Hour option and 90 Day option as the source of pricing problems.
http://www.gameinformer.com/b/featur...expensive.aspx