lucy24 - 10:08 pm on Aug 10, 2013 (gmt 0)
Very basic: (R * T) + O
You forgot M = what the market will bear.
Option A: charge as much as the product actually cost you, plus a reasonable profit margin. You don't need advice on this one, because you know better than anyone how much you've spent, so we have to assume you're looking at
Option B: how much can I charge and still find a buyer? This is assuming that if you sell a site for $10,000 and later find out that the buyer would have paid $500,000, you'll feel like an idiot. (If the reaction is "Oh well, I just wanted to unload it without losing money" then you're back in Option A.)
I strongly suspect that for meaningful advice on Option B, you'll need to venture into the paid sector of WebmasterWorld forums.