Appropriate Wheel Offset for 18" Wheels?

Anyways, I found some wheels that will fit my application, they cost more than the RP03's, but I called the distributor up and he's going to check with the wheel manufacturer on Monday to see if the wheel manufacturer has them in stock, as he only has the rears on him and I don't wait 6 months for wheels. He said, if needed, be he'd even cut the price down on these wheels so that they'd be cheaper than what I would have paid for the RP03's. Talk about awesome customer service!