The stock tires are pretty overkill. There's quality tires that are substantially cheaper than the Potenzas.
I went with Hancook myself, a pretty cheap tire. I paid $57 each for them. Definitely the weak point in handling on my car, but I plan on upgrading wheels eventually and didn't' want to buy two expensive sets.
Your best bet is to call a big tire retailer and tell them what you are looking for and what you want to spend and see what they recommend.