I always find it interesting that when people are offered some money to work out of their normal work schedule, such as the weekend, they look at the situation in many different ways.
Some people would be more than happy to pocket the extra cash, even if it's less than or equal to what they would make at their "normal" job. They just see it as bonus money and it goes above and beyond what they're already making so as long as they're busy they don't really care if they're making a bit less $ since in the end it's extra.
On the other hand, there are people that see a lot more value in their weekend, and free time in general. These people tend to be the ones that get upset when they have to work overtime at their regular job, even if that results in a bigger paycheck. It would take a lot more money than their regular pay rate for them to be motivated enough to do some side work on the weekend. If they regularly make $20 an hour they might not even do some work on the side for $30 or $40 an hour, whether it's because they can live without the extra bit of money or they just want to be able to enjoy their day off.
So the question is what kind of person are you and why? Does extra cash motivate you to accept offers for side jobs or are you one of those people that likes their weekend routine and it would take a hell of a lot of money to change that.