Want some real numbers? At this point there are two choices: a) Full Salary + 1-2% equity. or b) 8-10% equity vested over 4 years and minimum wage salary.
Paying full salary AND 10% equity, when the startup is already beyond ramen profitable stage is insane, it only makes sense if the guy is a real genius. I mean Larry Page/Sergey Brin level, and on top of that his knowledge, is something that you MUST have. Noone else in the world has that knowledge, and you NEED it to get your product to the next level. Then, and only then can you even consider that sort of deal