Hi Tbone,
Welcome to the forums. You have been given excellent advice. An unsmoked estate is a secondhand pipe that has never been smoked, not a single load of tobacco has ever been fired up in that pipe. Nothing. Nada.
When I first got into the hobby, ebay did not exist. The internet was something used only by large institutions.
I bought my pipes from brick and mortar stores, where I could learn about pipes and tobacco. Since then I've bought from B&M's, online dealers, and ebay. You can do well, or get suckered badly on ebay. Someone is about to pay $3650 or more for what is probably a fake Bo Nordh (a topic of another thread).
What I tell anyone who is contemplating buying on ebay is this. For the first several months, buy nothing. Pick out auctions and follow them to see how the marketplace operates, what prices are like for specific brands, shapes and finishes. Sure some cool pipes will come and go. So what? There will be more.
Don't out much faith in high percentage feedback ratings. A couple of the biggest swindlers I've encountered on ebay have 100% ratings. It's the bunk.
Wherever you turn to build your collection, always ask questions. A reputable seller will respond. If you don't like the pictures on an ebay listing, ask for better pictures. If the seller doesn't respond, walk away. You need to be knowledgeable, and even then, be prepared for the occasional unwelcome surprise.