Some of it is word of mouth, trial and error. I personally have had good luck with kits bought from several vendors. To name a few, Woodcraft, PSI, Woodturningz, Woodnwhimsies, Exotic Blanks, CSUSA, etc. I have had my run in with less quality kits imo, but I will keep that to myself. I think what sways me more than kit price sometimes is shipping cost. There can be a huge difference at times. Some of these are resellers of the same places kits too. I know many have their favorites as I do. Best suggestion I can give you is to do some Internet searches for any vendor you are thinking about and see if people give them good reviews or not. PSI has a review per items. Many times before I decide if I will try a kit I read the reviews. In the end though sometimes it will come down to what you discover for yourself or through people who buy from you. Hope that helps some. I am sure opinions will vary.