hi,
build yourself from scrap some transistor tester/s.that project is just a toy.
you'll learn more electronics by building one, analog or digital type.
buying the gm328 will only get you testing some transistors unable to be sure of the showed result and you'll discover day by day bug after bug in that 328 firmware and his limitations.it's not able for example capable to tell you "yes this triac is good", with a 10$ multimeter you can decide the triac status...all you got is some explaining why it's not working, the test current isn't capable opening the g-cathode junction bla bla bla.
I have a bjt which isn't detected as bjt since 8 firmware revisions with the gm328, I'll keep it just for reminding me how stupid I was throwing 20 bucks on a toy.
a simple analog bjt transistor tester takes 30 mins to build with some findings in your drawer, some hfe tester a little more hardware and the same 30 mins, except the documenting.
if you want the device, just buy a real used tester.
maybe I'm a bit too critical, but that's the latins
regards,pierre