Off the top of my head, without actually checking the measurements, that looks a lot like some plastic cases that come with electrical tape packaged in them. Might not be exactly what you want, but at first glance, its close...
Typically, most labs/schools use a 100-150mm by 15mm or 18mm tall petri dish. You can get them taller up to 25mm, the problem is no one seems to sell them in small packs in the 25mm tall size in plastic.... gotta buy them by the case it seems.
Only other suggestion I can say is to go to a local college and see if you can get them through the bookstore or if you know someone that works in a hospital lab or other diagnostics lab see if they can get you a few.