Having a tough time finding affordable office space? Join the club. Orange County has a 7 percent vacancy rate, among the lowest in the nation, while rental rates jumped almost 13 percent in the second quarter, to $2.47 per square foot per month. That's causing some companies to reconsider growth plans. Kurt Strasmann, regional managing director with brokerage Grubb & Ellis Co., tells the OC Register that there's a temptation to say "I don't want to pay that, let's look at what other options are available." But that's the point - for Class A office buildings, prices are high all over Southern California.