No one gives buying advice, so that you won't have anyone else to blame if your experience is shit. We've all gotten burned, probably a few times if you've been around for some years, so due diligence has to fall on each of us.
As for finding a good seller, look for someone (1) with an active thread, (2) with many recent positive reviews, that (3) posts recent chemical analysis of their products, performed by Janoshik's lab.
The good news is that testosterone cypionate is cheap, plentiful, and can get to your door pretty fast.
For what it's worth, if you're looking to lose some fat, test cyp will help a little bit. It'll mostly help you keep all of your muscle as you drop calories, so that more of the tissue you lose is fat. If you want something to assist that process, the safest and most effective compounds are the GLP-1/GIP drugs -- semaglutide and tirzepatide. Those are Ozempic and Mounjaro respectively.
Sema is devastatingly effective at killing appetite, but can have some unpleasant side effects. Tirzepatide will reduce your appetite slightly less effectively, but people tolerate it better. If you're eating clean and doing some resistance work, and your goal is to drop fat, that's probably all you need.