I'm going to go off the beaten path:
While what they are saying is true (if you're going to keep your straight ball, go cheap and plastic because in a worst case scenario you will have your spare ball for when you are ready to start hooking), I truly believe a lot of bowling is mental. If you have the means to purchase an expensive ball and you think it will help, DO IT!!! Just the fact you will have a ball custom drilled for your grip will make a huge difference.
My only advice is if you even THINK you might want to start hooking it at some point, it's probably best to look for something intermediate, or on the lower end of the spectrum. Reason being: You'll want to learn the proper technique, and if the ball you're throwing has monster hook, you'll be on the left side of the lane (assuming you're right handed) too often and you'll hate life.
Really consider what your budget is, and what will make you happiest with your bowling. This is just a fun hobby. It's not life or death. But if you don't already have your own shoes, BUY THE SHOES FIRST!!! The house balls are free, but you're wasting your money if you're still paying to rent bowling shoes (plus they're disgusting).
Bookmarks