I highly doubt she made as much as the GG kids for the OC, which started airing in 2003. If it was on now, I'm sure she would have made as much, but imo not back than. She has made a few movies, her line with Donna Karan, her advice column, etc. She also gets a ton of free stuff, like going to fashion shows are paid for. So my guess is, she's not hurting for cash, going by all that lunching and shopping she does.
I think she has the paps on retainer. She is photographed way too much, doing mundane things and not being a particularly good actress, not to have these people on her speed dial.