I've dealt a lot on the darknet markets for many years, and I'm currently serving time for it and I can tell you, like it is mentioned earlier in the thread, feds are all over it, they have undercover agents posing as both buyers and sellers, they were even involved in solving my case even though I'm based in EU
That being said, if your OPSEC is good, you use drops and common sense I wouldn't be too nervous about ordering a small amount for personal use, as I've said, I did it for many years, amounts way larger than personal use, and I only got caught in the end because I got lazy and fucked up.
I do disagree with something however.
My experience is that quality, purity and general product satisfaction is way higher on darknet markets than when buying from someone locally.. The things @
mothered say, they all apply when buying locally too, but online you have peer reviews of all products which means that if there is an unpure or substandard product, sellers reviews will quickly reflect this and as long as you buy from someone with a lot of good reviews, you are most likely to get a high quality, unadulterated product, shipped with excellent stealth. Usually you can cut out some middlemen as well, meaning lower prices and better products.
I am not condoning this, I clearly cannot since I'm currently locked up for doing this shit, but just wanted to share my experience with you. It can be good, it can be very lucrative, and it can be pretty much just as secure as dealing locally, if you know what you are doing.
You should never just think what the hell and just order something to your own address, you never know when the dealer is gonna get busted, and if he has bad opsec and saved your address in plain text or something.