The current layout is filled up. We've added as many sidings & yards as the space will allow and built several shelves. We've even added a new siding off of one of our passing sidings and named it "engine overflow".
I'm still buying but at this point when a new addition arrives it means something else needs to be stored (for now).
I'm currently house shopping with plans to have the majority of the finished basement dedicated to a large layout which will allow for more trains.
I don't have a limit, but as I've gotten more and more items I get more selective. And, if I buy a newer / better version of an engine, I sell the older one. I plan on selling some excess rolling stock as well.
The shopping / buying won't stop as long as I have the money to spend and as long as new and better items get made.
