There are black plastic and chrome ones available on Ebay. However, the shipping cost is almost as much as the frame itself. I would be in the market for a chrome frame with the Lotus logo in color on it. Or I may do without a frame as I've done on my Miata.
[Sorry, Symbolic, but I definitely won't keep yours on].
For those looking for a frame for the license plate. I went to walmart, bought a $10 black plastic frame and replaced the hex bolts mounting bolts with stainless steel allen head bolts, remember chapman and K I S S strategy.