I would turn down a 3% commission just on the commission rate alone. Not saying I'd ask 20%, but if I was doing all the legwork, 5-10% would be fair - not including expenses (of which $50k would be absolutely fair and reasonable).

Equating $300k in terms of an annual salary equivalent is poverty thinking. The experience and polish necessary to impress VC firms to the tune of $10M, requires a finesse that would not be salivating at low to mid six figures.

Also, a $580k seed round with no MVP is a red flag in and of itself.

Did they have at least good design?