How much do executives at similarly sized organizations make? Moreover, if you want to cut executive salaries, how do you avoid the "pay peanuts, get monkeys" problem? Mozilla has nearly 1.5B in assets. A cheaper CEO might save you a few million, but cause far more than that in damage to the organization.
Perhaps linking a greater share of pay to success would be a good idea. How about $200,000 + $1 million per percentage of Firefox market share? In recent years, CEO pay has doubled while Firefox appears to be in terminal decline.