I used to charge $10 or $15 for a 500 word article. I haven't freelanced in a while though since I started post grad studies and I'm also working on building my own stuff now. I sometimes hire other people to write stuff for me and the lowest I normally pay is $5 per 400-500 words. I know it's not much but I don't expect quality stuff, just semi decent ones for backlinks. Well I used to do this at least before all the google algo mayham. Now I'm trying to stay safe and write everything myself even the ones I use for article marketing (ezines, hubpages, squidoo, etc...). Highest per post rate I ever had was $25 for 800-1000 words from an old client. But that was way back and I've only had about 2 or 3 clients who paid me more than $15 a post.

Hope that helps. But like I said this was way back, maybe a year or so ago. And I'm an asian writer FYI and as I understand it, people form english speaking countries get paid way more so you might want to factor in your geographic location.