Have a look at salvage yards and the tip shops, they are packed with them. I had one made a few years ago from a cast iron bed head and end, turned one upside down and a metal fabricator weld them, the handyman installed it, I love it, mind you, that's a front gate, the driveway gates are ancient from the old house over the road.
If you are a bit of a handyman, you can get all the bits you require from Bunnings - premade gate frames made of gal steel, with hinges, instructions and can be trimmed to size (need an angle grinder), etc. I made one for the side of our last PPoR - took a day to do...rapid-set concrete in the posts, then measure and cut the frame, assemble that, attach hinges to posts, cut and attach wooden slats (need a drill for this part), hang gate and stain slats. Not a good photo, but you can see it down the right side of the house. (Incidentally; that letter box took almost a day to do as well! )
Already got a quote fron dunn and farrugia they were expensive. Im after a aluminion gate with horizontal slatting. Im pretty handy however the side of the house is not level so the gate needs to be tapered if thats the correct word. Thats a freaking awesome letter box dude. Lol
