I believe one of the major drivers of IoT will be the widespread availability of cheap yet powerful micro controllers and free software. Its this combination that is driving a lot of experimentation and Kickstarter projects that will bring us some game changing IoT products. Here are 10 very small (and fairly cheap) boards that you can use to get something prototyped and working: 10 tiny cheap dev boards
Here's a little insider tip though, if you go to an electronics trade show like Design West in San Jose, Embedded World in Germany or many other regional events you may find companies like STMicro, NXP, TI, Atmel and Freescale giving away USB powered dev boards (and software) for free. However you get the board isn't as important as plugging it in and finding out how easy it is to get it working. To me this is the democratization of technology and a time when anyone can design and build useful electronics and possibly change the world. Go and get a board!