Using back of the envelope math, let's assume the average flight in an ERJ is 2 hours (it's actually much less so this is conservative). Let's assume the average plane leaves with an also conservative 50 pax. That means each $1 a pax pays extra is $25/hr. Doubling FO pay would cost another $50 an hr and doubling CA pay is another $100 an hr (again, both conservative). That's $150 an hr extra cost, or $300 for an average 2 hr flight. 300/25 = $12 per ticket extra.

I realized an error in my math while typing it out, so its roughly 12 instead of 6. Still, the point is the same. Hardly a deal breaker, and these are all conservative numbers so the true cost would be lower.