Just do a google search for N scale lumber loads. There are a lot out there including the wrapped loads. And Ebay has got a few listed.
A couple pics of what I am working on - agree with John - lots of stuff out there easy to find some not so easy to find though. The wrapped load is off of ebay. The frames-I am working on, secure/bracing detail now. This is in progress (no option to rotate view here) I found some really nice lumber loads - many dimensional loads lots of diff sizes that you can get with the small banding that looks really nice (paint red/green ends). I don't think I can post the pics because I have not completed the builds and the pic I have has the online store stamp which I don't see as an advertiser here (just in case I don't want to violate policies)
I laser engrave my own lumber loads on clear maple stock. This makes them very heavy (!) and easy to unload at their destination then reload at the mill...
