I'm going to try it buy my question is where is the most legitimate place to buy such product. Can I find it in a store or only can find it on the net?

Where do you live, In China, you go to the drug store and buy it.

In the US, you go to the doctor who gives you a prescription and you go to the drug store and buy it.

In the US and many nations it is not legal to buy it ( or sell it) without a prescription.

If you buy it online in a area where you need a prescription, you risk poor quality, fake medication. If they ( and you ) are willing to break the law and buy and sell prescription medication illegally why would they worry about cheating you.

You could not even sue them for damages since you can't sue for a illegal action

I am from the US and would like to get some recommendation on the easiest way to get this product.