CONVINCE DAD TO BUY A METAL MOUTHPEICE?

i play the tenor sax for 2-3 years and i got a dukoff from a friends that he gave me #8. I went to samash and tried ottolink mouthpieces. I borrow my friends 7 and i tried 4 and 6. i like it, it is $149. and i really want to buy it. what can i do to convince him?