Unfortunately, I do not. I’m not a cosplayer and I don’t have any experience buying costumes/props/etc. However, I can tell you not to buy from eBay or Milanoo; they lure people in because they’re cheap, but the quality is often horrific and nothing like the photos (that’s if you get it at all).
Normally I’d say something like “don’t buy costumes that look like they’re made out of nasty super-cheap shiny costume satin because it never looks flattering on anyone, ever, wrinkles constantly and just does not look good” - but they’re usually the cheapest, and it’s a big step up in price for even slightly better quality; so if it’s just a Hallowe’en costume that you don’t plan to ever wear again, and the most important point is that people recognise you as Sailor Moon, then really it wouldn’t be that bad. But if you plan on wearing it more than a couple of times, especially if you plan on wearing it to a convention, spending that little extra cash will make a world of difference.
As for actual links, I’m going to ask my followers here to send recommend some! Send them her way, cosplayers!