It may be worth your time to pick up a set of universal spacers and try them first. A lot of owners run them with absolutely no issues. You should be able to get them at about any auto parts or tire store for around $20-30. The only real possible issue with these spacers is possible vibrations since they are not hub or wheel centric and could therefore be installed off center. For the price and availability as compared to hub centric spacers, you really don't have anything to lose by trying. Worse case scenario is you get vibes and have to order the hub centrics after all.
If you do go with hub centric I would call the folks at Motorsport Tech. I'm wanting to say a set of two (that's really all you need) hub centric spacers was running around $125 but I may be off on that. Call em' up....they will help you.