Sometimes you DO (sort of) get something for nothing. For a recent project, I tracked down a Plasticville Union Station kit. (It was missing the front stairs, but that's another story) What it did have was two platform extensions at the back, which were surplus to requirements. Each section also had two upright supports for a section of platform roof.

I took these supports, and glued them to pieces of sintra scored to represent pavement. Clear plastic (from broken CD covers) was affixed between the supports, and the roof was attached. Trash cans, benches, posters and weathering then completed my bus stops. I now have a pair of interesting terrain pieces, made from leftovers. Posters were made from images found on the internet.