I have never bought yarn but I have bought and sold other things. Every once in a great while you will get a "bad" seller (has happened to me once)and thankfully I didn't loose alot of money but I lost it. Just be very careful, read the persons feedback and if they have any negative comments, see what they are. If the comments say, didn't get the right stuff, never received etc etc. then I would say you would be taking a risk buying from that seller. Basically just use good judgement.