should depend on what credit you have available and your ability to pay it off. Medical costs, funeral expenses, etc. can be very costly, but if you just have to wait for the next paycheck to take care of it, then you can rely on credit. If not, I'd lean towards having $1,500 in cash for emergencies only.
After that, you can create more slack in your budget based on expenditure potential (which should be a factor of your income and your assets). For example, if you have an older home or car, maintenance or replacement costs should be considered.