Learning how to navigate SR takes a while and you will get your eye in after a few months knowing what to look for and have a few contacts on the forums you can share info with. Best thing you can do is compile a list of the vendors who you like the look of i.e. been around a while, have solid feedback and plenty of transactions under their belt. Then find the review threads for those vendors, if you can't find them and there are no links to them on the vendors page create a new one asking for others to share there experiences. If the vendor is worth a look it shouldn't be too hard to find them