I like these Monstera leaves from Tozai; the combination of the natural form and the gold finish is kind of fun. They sell for $20 each, which is not terribly expensive, but I figured I could do it for less. I looked around and couldn't find any monstera leaves, but I liked the shape of these water lily stems at Hobby Lobby. I chose a couple, trimmed the stems to fit my vase, and then gave each a few coats of Rust-oleum "hammered" spray paint in gold.
A couple tips: choose a stem that has some relief to it and is not completely flat with the detail just painted on. You may also want to choose something wired as that gives you more flexibility in molding it to the size and shape you want. Also, I like the hammered finish of this spray paint as it covers up the "fabric and plastic faux plant" look a little bit and makes the leaf look like it's truly made of metal.
After letting the paint dry, I wiped on some Rub 'n Buff and buffed it off to add some more shine.
I threw them in a vase and we were good to go! And the two leaves plus spray paint cost about $9, I think. Not bad!