I think fair value for an SP should be determined like this: if it were you doing the service, how much would you charge?
So I think of it like this: I'm the SP, and I'm going to take most of you customers and be expected to service you for money.
I'm going to have to listen to your inane blatherings, your infantile emotions, your dumb moral conflicts about having a wife/S.O. and justifications for being with me. I'm going to have to touch your fat, hairy, disgusting body and still make you feel like you're one of the most desirable men I've ever met. Worse still, many of you want me to kiss you deeply as though you were my boyfriend even though I have no idea where your mouth has been and how much tooth decay you have, and many of you are going to pressure me to suck your dick without a condom. Some of you fucking bastards even have diseases that you know about, or don't care to know about, and don't care if you spread them to me. Then many of you dishonor me by complaining about the price or haggling it down.
I'd charge at least $10,000. Frankly, no price is worth it because I'm worth more than that. The sad thing is that most SPs think they are worth $200/hr or less, which means to me they see themselves as basically worthless.