[Joe Nation]

Lensbaby do a 12mm FE for about $250 US. I've never used one, but if their tilt lenses and optics are anything to go by it will be fine if you don't mind a not-perfect IQ. If you want the crispest, brightest FE shots I'd suggest the DA 10-17 based on what I've heard about it. But the Lensbaby is pretty cheap and will do a better job than an adaptor. And if you fancy it, you can fit the FE optic into their tilting lens bodies so could give selective focus a go too.