Lets say that the annual liquid compensation difference is $200K. At minimum, I would ask for equity that matches $300K (18 months at the difference) at the sam

Lets say that the annual liquid compensation difference is $200K. At minimum, I would ask for equity that matches $300K (18 months at the difference) at the same valuation as investors in the seed round received. Coming on as an employee at this point is at least as risky as the investors putting in money at this point. Even after negotiating that equity stake you should be fully prepared to write it off as a loss and move on in 18 months to 2 years. Most start-ups will not succeed in significant manner.