Darren LaCroix, a successful professional speaker who's well known in Toastmasters because he's the 2001 World Champion of Public Speaking, has a comprehensive program called "Get Paid to Speak by Next Week." I went through the whole thing and would recommend it for anyone new to pro speaking who wants to break in. It starts from the level of total beginner and explains all the how-to details. Darren also includes dozens of forms and tools to get there you a lot quicker, and he shares specific figures. He got only $75 for his first paid speech and now earns 100x that.
Check out his site:
Presentation Tips, Getting Funnier and Keynote Speaking with Darren LaCroix
I should mention that Darren is a friend, so I'm not completely impartial. He moved to Vegas and belongs to the same Toastmasters club as me.
Toastmasters is a good place to build your speaking skills, but it won't teach you the business side of speaking, which is a whole other world to discover.