I like the concept and have longed for this for some time, but I'm not a fan of the big sign up button without an easy way to know the price (maybe t's through that button? I dunno and don't want to put the effort in if the price isn't reasonable). My suggestion: make a pricing link or put pricing into on the front page.
(I'm on a mobile device, so these comments may not apply to a full size browser.)
(I'm on a mobile device, so these comments may not apply to a full size browser.)