Ebay is a good source, but I've had most of my luck at train shows where I can see the parts and make sure they are not broken or cracked. My first set was the All Aboard set with 8 panels. Still have it, but had to replace quite a few trees, street lamps and other signs as well as epoxy some panels that got stepped on and cracked. I am repairing the whistle panel as well as the underneath wiring on the panels.
I think that Train Repair Parts still has some panel parts as well as Portlines.
