There is a diecast (1/48 IIRC) but that is all I know of other than the Revell 109 kit mentioned above. I think the diecast is a Testors kit but that may not be correct.
HeavyArty thanks for the link to the MH-68 decals, I have had the idea of converting a 109 into a USCG MH-68 sometime after I finish the Fireball HH-60 Jayhawk conversion. Since I haven't even started that one yet who knows when I'll get to the MH-68, but at least now I know where to get decals. I wonder what the chances are Revell will do a USCG version of the A-109.