I would guess that your price per profile can only be determined once you can figure out what the bookmark or returning visiting rate of the profiles are. Having 500,000 profiles is great, but if they only return once a year what's the point.
Sites like Facebook and myspace make money, don't kid yourself. However they didn't make their money over night. They have very valuable information that I'm convinced they either sell, lease, use in some sort of product targeting way.
They have your location,sex,email address, and age. So with just that info alone, they can determine things like, if you're a 38 yr old female with two kids, chances are you're a bit over weight and they can get you on some sort of weight loss product. If you're a single 33 yr old male they'll sell you on dating sites, or some type of cheap fitness plan.
These are just some of the basic things they can target, imagine what a trained mainstream marketing firm can come up with, but it all relies on the pattern of the surfer. Find that out and you'll find out what they're worth.
Hope that helps.
