When I was looking for used LGB track, what I found on ebay and Craig's list were old dirty railed track, some with broken ties. The worst were the bent rail connectors. If you run track power this is all a problem. New track, with nice tight rail connectors, is what I decided to use.
The best retailer online that I found, price and service, Only Trains.
Only Trains
Add they don't charge PA sales tax!