If the current situation continues, Amazon and other huge businesses will consolidate their monopoly and there won't be any small businesses.
So you might like to support small and preferably local businesses whenever possible.
This site https://www.bestprice.gr
...provides links to Greek suppliers of whatever you type into the search box.
Sometimes typing in English will find what you want. Other times you'll need to use a dictionary.
You'll also need to know the common words used by the various shopping cart pages. The more often you order, the easier it becomes. (Keep a note of the words.)
(I set it to search for isopropyl alcohol as an example but the url tag doesn't work so copy-paste.)
Delivery is generally quicker than Amazon. Sometimes you get a choice of, say, ELTA or ACS courier and it's remarkably cheap.