USGBC's website makes it difficult to sort for the free courses, but you can find the free ones that count toward the 6 LEED-specific hours if you're persistent.  Go to www.usgbc.org, click Education, Continuing Ed, then in the Filters go to Continuing Ed and select the rating system for which you're accredited, then keep scrolling down to find the free ones.  My recollection is that there are several Trane courses, one or two Kohler, and at least 2 about central vacuum systems that meet the LEED-specific requirements for BD+C.  You have to find the ones that specifically show the BD+C icon.  If they just show the USGBC icon they'll count toward the other 24 general credits, but not toward the 6 LEED-specific ones.

  For my first 2-year period I was able to find enough LEED-specific credits to meet all the requirements for free, but by the 2nd there weren't enough that I hadn't taken already so I've ended up having to pay for some hours.

You can also meet the LEED-specific credits by working on registered LEED projects.

http://www.hanleywooduniversit...

Seem to be some free ones there.

There are a few there that do meet the LEED-specific credits for BD+C. Make sure to use the ones that say the name of the specialty. The problem is that the vast majority of the Hanley Wood, McGraw Hill, and other CEU providers' offerings just provide "general" USGBC credits.  Those aren't hard to get, and in fact you can report pretty much anything with a sustainable theme, even if it's not specifically USGBC-listed, and USGBC will accept it toward the 24 required general credits.  The hard ones to get are the 6 "LEED specific" credits, which have to include the logo of the specialty for which you're accredited (such as BD+C).

The continuing ed requirements are 6 LEED-specific + 24 general credits for every 2-year renewal period after the first.