Let's sum it up with this. At per gram levels, SWIY won't get much quality. Let's say that you bump it up to 3.5g levels and SWIY has a lot more options. You see SWIM
years ago would purchase 3.5g's on a somewhat regular basis. Each time is was a couple small rocks and mostly powder which in the world of coke
, means lots of cut. SWIM's most recent 3.5g's was well a bit more than he bargained for. Not only was it pretty much weighed out right (it was like 3.2-3.3g worth of powder and some crack
to go with it) which was a surprise in and of itself. However what the bag contained was top level, three large compressed rocks with just a little bit of powder.
The point of all this, if you're looking for purity, save your money. Buy two things, 1) 3.5g minimum and 2) LOTS of equipment to purify it via the acetone wash that's available at the top of the main cocaine
and crack page. Too lazy to post a link right now.
Here's SWIM's opinion, you buy a gram of even the best looking coke and you're not gonna want to loose any from washing it. However, once you pour out the whole 3.5g's and get it into a nice smooth powder you'll realize that you've got a good bit to work with. Just look at what you've got and you'll soon give into the idea of washing it. Or at least some of it. Good way to limit use too. Buy 3.5g's and wash half of it. It'll take a while for it to be ready anyway. Now let's admit, ~1.25g is usually enough to get your fix. Surely you'll want more but the thought that you'll have another batch ready soon should sooth you. Do you're nightly routine, and try to get some sleep. You'll sleep like a baby knowing that the next day you'll have access to some of the best coke you've ever done. Not to mention it'll be waaaaay better than anything you can find on the street.
The simple fact is, it all depends on a couple things 1) location (closer to the coast or neighboring border = the fewer hands it goes through therefore the better the quality), 2) who you know (it's not like you can stand on the side of the road with a sign asking for coke), 3) Amount (look at it like a business deal, you buy a pack of gum, no matter what the profit margin, the seller isn't going to make much. However, if you buy a much more expensive item, and if you're lucky, got a good location, and a good dealer, and you will very likely end up with more bang for your buck so to speak)
Simple answer to the OP's question, UTFSE
and you'll find threads trying to answer this. Other than that, SWIM thinks it depends on the three things above. However, for most of us, having all or any of those are hard. SWIM's suggestion is to perfect the acetone wash procedure. Much cleaner product and therefore arguably more safe of a product.