As a student at a top worldwide university, I can tell you we order a lot more stuff off Amazon and eBay than you'd think. There's an awkward middle ground where you either buy something cheap or make it yourself because labour is basically free in academia thanks to the large amount of students and staff but grant money is not.

But what do you down with the Thorlabs Lab Snacks? I thought that was the main reason grad students ordered things from them.

yes ! but it also assumes you have: a good optical breadboard + bench + dampeners, a beautiful set of lenses, all sorts of nice lasers and kinematic mounts and linear stages etc etc

so yes, we _also_ (back in my phd lab) built equipment in that sense, but there was a pretty good foundation of Fairly Fancy stuff already sitting around !