I was gonna comment on that too but to be honest I don't know what the average is so I didn't want to go around waving false figures.

I've only been freelancing for two months or so, but I've worked at rates ranging from $5-$40/hour. It really depends on who you work for. Working for individuals of course pays less than working for companies, and companies are more responsible and you have more security working for them. I never would have worked for $5/hour of my own accord, that was just me being stupid and not signing a contract because I was so giddy about my first job. I wound up only getting half of the initially discussed payment.

I think something around 15-20 is common though, right? I know flash games get their revenue from being picked up by a portal - so your income might be a % of that purchase price. It actually might be cheaper for them to pay you something like $15 an hour, depending on how much work is going into it. Get a detailed list of all the assets you'll need to create, from that you should be able to determine roughly how many hours.

Not all clients are tight. If you have that gut feeling tearing you up inside that your time isn't being purchased for the right amount, don't take the job. : )