tell your dad to get you a kilo tt and then get a job or work on something with a future to show him you're worth a 600 dollar bike.

hell, maybe if you really impress him with how much of a good kid you are, or if you show him what a good man you'll grow up to be, he'll want to buy you a nicer bike.

honestly 600 is a tough cap because you can't get much better with 600 than you can get for 300 with the kilo. a kilo WT is another great option in your price range.