Semikart is truly a blessing for us DIY guys, because we can get most of the quality electronics components that we can think of without worrying about dodgy fakes, no GST needed, no stuck in custom problems, straight to our home. I ordered few things over the last 5 years.
Benefit of sites like mouser (my favorite), element14, digikey etc is that you can view legit datasheets, even for 5 cent resistor. This kind of stuff is missing when we look at our local DIY sites.
The packaging quality that you get from these sites is crazy (no semikart doesn't open them), for example I ordered some microcontrollers from mouser through semikart, it was in sealed air tight packaging, when I opened it, there was moisture card inside which changes it's color when the moister goes above some threshold level, indicating that the product is not exposed to high moisture level. The quality of the cardboard, the form, the antistatic bags is impressive.
Also great for batteries, you can get genuine 18650 cells from panasonic, LG, etc with their actual datasheets.
Medical/Space grade components are also there and even Military grade for the crazy ones.
Their search engine is amazing, you just have to add the part number of your component and it will fetch prices for it from the all the sites.
Semikart is a part supplier they do add their own processing fee to the final cost. So if you have a business you would probably order directly from those sites and not involve semikart.