MiniVend is normally free of charge, and is distributed under the GNU general public license. This means that individuals and organizations, both commercial and non-commercial, may use MiniVend without charge. If you modify and redistribute it, there are certain obligations you must fulfill. See the file Copying which came with your MiniVend distribution for the full license.
MiniVend is not guaranteed to be supported other than by making full source code available. If it breaks you get to keep both pieces. However, the author is always looking to improve MiniVend and sometimes answers questions. The more concise and better-researched your question, the more likely it is to get an answer. No tutorials will be provided, though. You have to learn all of this stuff on your own, or use the MiniVend mail list and hope that someone will help you.