What Next?

Happy Humpday to everyone in blogland...hope you are having  a relaxing evening wherever you are in the world!  I recently got stiffed on an auction from a new buyer with no feedback and although I KNOW we all had to start somewhere to build up those lovely little stars BUT....I have noticed some sellers put a disclaimer on their auctions that if you have less than a certain feedback rating you must contact them before you bid.  Is that legal per ebay........does it sound rude to buyers?  Any suggestions to curb this type of thing from happening again?