Think you are missing a beat by not having affiliate links to those Display Dummy Plugs! Would certainly order via you as a cost free way of donating should I come to need this type of software.
And yeah I regularly do that kind of thing :) Especially with single dev projects, I prefer spending on them than the big ones like Mozilla, Wikipedia etc. They already have plenty of ways to get themselves on the map for donations.
So even if the commission on the Display Dummy Plug would be peanuts, you can still generate a decent revenue stream from capturing commissions on ancillary and unrelated add to cart actions within that 24 hour window.
[1] https://affiliate-program.amazon.com/help/node/topic/G9SMD8T...