What Should I DO?!!!???

I need a job asap. I have a 2nd interview today at 4. But its not REALLY an interview, they want me to work for free. they want to observe me and see how i would act if I DID have the job. To give me a chance to see if I would like it and to let them watch me and see if I would be a good fit. They already told me that I would make 7.50 an hour and I would work 15-20hrs a week. I think that is 2 little money. But im not making ANY right now, and I dont wanna work there and quit after a wk or 2 because something better came along. my options are take it and have some money, or dont take it and try harder to find somethign else that pays more? I dont want to settle. If i dont I have to rely on asking my parents to help me out a bit! My dad will, he always does. But I dont really want to keep asking him for stuff. My mum always says shes broke so she cant help. OY, I just dont want to settle on this