The one time I charged by the hour (I can't provide details about the project), a long-time but desperate client offered me $500 for one hour and felt I undercharged by the time I finished. Talk about pressure ...

The only issue I found with EFA was that one of the members "reports the freelance editors listed there are not vetted" ( pred-ed.com/peesle.ht). I've joined as a guest member but haven't had time to explore the site but I'll let you know what I find.
Update:While the guest membership for the EFA is severely restricted, I've found some information about this association that seems to support its credibility. They have about 3,000 paid members more or less and receive around 400 job listings each year. The association maintains a Facebook page and LinkedIn account that are restricted to paid members only (they are also on Twitter as EFA International). Paid members also receive some nominal discounts on health and dental insurance, a subscription to an online freelancing magazine, a 50% discount on ZipCar annual memberships and discounted usage rates, online educational programs and publications and a few other freelancer-specific bennies including networking opportunities.
I'm not convinced that this is enough bang for the buck. I'd probably be more interested in joining as a paid member if there were more job listings (but the 400 they post may be highly lucrative).