A few years ago, CZT detectors made by eV Products showed up in quantity on eBay. Pretty much everyone interested in radioactivity seemed to snap one up back then. It took a fairly long time for folks to figure out how to use them well! But they're really not bad, especially for the size.

Here's some spectra with 3% FWHM @ 662 keV:

https://maximus.energy/index.php/2020/05/01/gamma-spectrosco...