I bought a cheapo ($117) carbon fiber (fake?) spoiler off eBay. Shipped quickly, packed well, fits well, looks good! There's a bunch of them on eBay - I suspect there's one or two shops in China making them and dozens selling them. This spoiler actually sits on top of the trunk edge, but has a ridge on the bottom that contacts the trunk edge as you push the spoiler forward, so it's properly aligned. Just measure the distances between the spoiler ends and the trunk edge (and mark with masking tape) to make sure the spoiler is centered.
Vistan