The second sentence sounds a bit strange and isn't completely clear, I think. More natural ways to say what I think you mean would be, "I want to have spending money" or "I want to have money to spend". "Spending money" is a common term referring to money to spend on leisure activities, non-essential purchases, etc. - if that's what you mean. If you're talking about working, this would sound less repetitive: "I decided to work to have spending money."