Ive bought pretty much all my glassware and lab equipment off amazon and here and there some specialty stuff from ebay. Ive been a hobby (amateur) chemist for many years, there are many people who do this, not to mention glassware poses no threat to the DEA, its the chems they focus on. No one has ever inquired about anything ive ever bought.
But as far as buying chems from amazon? youre good to go... They dont sell anything questionable so its pretty safe. There does seem to be a lot of like moderately illegal shit on ebay, like iodine, or occasionally LiAlH4 shows up or something like that... I dont know how to advise you there. Im fairly certain its fine. though. Some companies slip up i guess, or dont have it together, smaller companies in my experience. They allow you to buy something that usually considered something theyd sell to businesses only or wont ship to a residential address. For example buying bromoethane requires you to have a license pretty much everywhere ive been online, but after enough searching i found one that doesnt require a license, or didnt categorize it as a bad chem.... or something. I only buy it from them once and im not buying in high enough quantities to spook anyone, so its not likely to be an issue (like 250-500ml one time). But the heavy stuff like the DEA list 1 chemicals, or whatever the organization for your country is, forget it..... you get good at synthesizing your own shit. So when it comes to chems, thats when you have to be more strategic....
Im in a unique situation, im lucky enough to have an old school chem supply store nearby. They primarily sell to colleges and businesses locally. They arent really too common since the internet is around. But ive spent a few years in there and theyve gotten to know me as just a backyard/amateur/hobby chemist, and i was legitimately this for a while.... So when it came time to me getting into the fun stuff, acquiring moderately difficult stuff like sodium nitrite, sodium borohydride, and even potassium permanganate it was easy, they were like "sure here ya go, have fun, what are you making this time?" **insert well thought out lie, and describe a reaction it would be used in some dumb college level thing that makes you look like youre just wasting your time on something assinine** .... You'll find your way.
also give this a read for some basics. Its from the 90s but the approach is still similar enough for it to still be definitely relevent.