You can't live without a salary, and you can't be productive unless you're alive. Putting money into a start up and expecting the founders to not take a salary would be like putting money into a bakery and expecting the owners not to buy flour.
As far as what is acceptable, it depends on your market, the idea, the investors, and the founders. I've seen as low as 40k (approx 50% market value for the founders if they were employees) and higher than 100k.
As far as what is acceptable, it depends on your market, the idea, the investors, and the founders. I've seen as low as 40k (approx 50% market value for the founders if they were employees) and higher than 100k.