I should also ask, what qualifies as "help 2 or 3 times" and what kind of equity would you envisage? (I know it is highly dependent on multiple factors, but I am curious for people's experiences...)
http://www.saastr.com/on-paying-your-mentors-and-advisors-th...
You're probably thinking, as you're accustomed, about your time in units of billable hours. You may want to reframe that in terms like those Lemkin describes. If introductions are not really your currency, an actionable breakthrough communicated might be. Or a fundraising / sales deck you review & provide detailed feedback on.