This looks like the amazon solution I need. It seems to work just fine- no frills. Without instructions (maybe I missed them?), it was hard to know what the "donation" parameter was for. After experimenting, I found that options 1 & 2 put somebody else's associate id in the link, while option three, put in ours. It must be for if we'd prefer to credit the author as a donation? Just to be sure I searched for all instances of the other associate id and replaced it with ours in the file.
Thanks for figuring out how to make this work. Would appreciate more explanation about configuration.