Where do we get Sprite fonts?
I am including a few in my example capx, but mainly you make them to fit your project's theme. Using your favorite image editing software you draw or place letters from a font you have rights to use in a grid. See the "How" section on page 3.
GiveYourFontsMono (Tool)
The simpler solution is to use a conversion tool like Blackhornet's "GiveYourFontsMono" program for PC. It will convert a chosen font, sized to a grid, automatically set the widths, and output them to a image plus a text file where you can copy them to the project. He also has come up with a JSON solution that makes copy & pasting in the list much less tedious.
The example Capx also shows both methods.
See this thread for the latest version of "GiveYourFontsMono:"
http://www.scirra.com/forum/sprite-font-generator_topic72160.html
Font Sources
You can get free and purchasable fonts from around the web, just check the license to make sure you can use them. Here are a few free websites:
http://www.1001fonts.com/free-fonts-for-commercial-use.html
http://www.fontsquirrel.com/
http://www.google.com/fonts/ (all opensource! http://www.google.com/fonts/#AboutPlace:about )
Or you can make you own TrueType Font for free here:
http://fontstruct.fontshop.com
The font's I'm including are licensed to allow commercial use, modification, and redistribution, as I am making them available publicly in this altered form. You wouldn't require permission for redistribution, but you may need embed permission. You can always contact the author and get permission as well. You should be able to use these fonts in your own projects, as long as you include the corresponding credits and/or license.
Font Credits
Bradley Gratis by Justin Callaghan
http://www.1001fonts.com/bradley-gratis-font.html#license
Cherry Cream Soda by Font Diner
http://www.google.com/fonts/specimen/Cherry Cream Soda
Sansita One by Pablo Cosgaya
http://www.google.com/fonts/specimen/Sansita One