the darknet markets are much like ebay, the vendors have ratings and feedback etc so it not hard to not get ripped off, also most have forums so you can do some research on the vendor before buying.Darknet I guess is the best option but getting ripped off is highly likely no? I'd have no idea which guys are trustworthy and which are not, or is it a case of sending the cash and wait to see if I've been scammed or not?
not to mention your in this thread where theres more than a few darknet junkies lol who could point you to the right vendors for what you want.