I would say India for Drugs is not a bad idea - if you're worried it's "from" China.
Open up the phone book. I'm sure you can find one within a day.
Chemists like money. Especially when it's not even a controlled drug.
As someone with only a high school level of chemistry training I would check the melting temperature.
Although seriously get it professionally tested. The delta between USA prices and India/China prices is so high a lab test will barely change the margins.
The first steps would be assay and impurity tests for the active pharmaceutical ingredients (API). If you bought tablets you'd probably want to do dissolution as well.
If everything looked fine after that, I'd still be concerned about uniformity. If you just performed dissolution on half a dozen tablets, how do you know all the tablets are the same from the whole supply?
Next question is then stability. What happens to the API over an extended time period? Does it deteriorate due to climate or poor storage conditions?
The main issue is quality control. Even an approved generic has to file with the FDA (or equivalent of wherever you are) concerning processes, batch sizes, critical quality attributes etc.
Then again:
https://peterattiamd.com/katherineeban/
> The story of Ranbaxy: An Indian drug company whose business model was fraud and deceit [40:45]
There are lab services that will run samples through a mass spec and report the results.
Or an insoluble polymorph.
Realistically, a lot of cancer drugs are injectables, ramping up the risk of something going awry when you inject the powder you will have to handle.