BaM, I can't really say where the gate comes from, as it was a gift from our friend Bailey03.
Perhaps I can help with that then. Those gates are model train scenery. The company that makes them is called Busch. Search for 'Busch HO 6016' and they're called 'Fence with Gate'
I believe I picked them up from
euromodeltrains (which is based in NJ). Those fences are plastic, by the way. If you're looking for etched brass gates here are some options...
This guy on ebay has some forge world etched brass. I don't see them over at the forge world site, so maybe they're discontinued or just mislabeled.
http://www.ebay.com/sch/allanbrookes/m.html?_nkw=&_armrs=1&_ipg=&_from=
ScaleLink is a nice resource for a lot of scenery stuff. They have some really cool ornate gates and other etched brass scenery stuff.
http://www.scalelink.co.uk/acatalog/Etched_Brass_Frets___Photo_decoupe.html
