Gotta build one
Might as well relocate your exhaust while you're at it.
Mach2 on the boards is fabricating a full front splitter, undertray, diffuser after a few conversations with me. Might want to ask him about his project.
Carbon fiber or aluminum are good choices, aluminum might be better for the undertray as it won't break if you bottom out or hit a speedbump (not to mention easier to work with).