Interesting concept. Short but enjoyable.
Buying only one of each. New people comes from the edges, so I only click along the edges - letting the things I've purchased handle the center. Click. Click a lot. (and possibly mute the audio from the tab, the noise gets to you quickly if you click all the time.)
I did a less frantic play-through first though, where I purchased multiple of each. That was more laid back and honestly more enjoyable with some music in the background, but it got me thinking if I could nail down a better time if only i tried.