Ways for a 13 year old to make money??? Parents against an allowance.?

Well In need to make $150 dollars by the end of summer so I can adopt this amazing cat named Pepperoni. My parents think that an allowance will spoil me so I can save up like that. They will however pay for food in half, and it has a vet exam, spayed, microchip, flea treatment, and current vaccinations. I have never had a pet bigger than Mocha, my Hamster. What else would it take to care for this kitten? And how do I convince my parents I am responsible enough? How much does pet Insurance cost? Any one have any ideas? Remember Best Answer gets 10 pts. Ill also email you a picture of the cat.