Look into building one yourself. I built one for my O'Day 35 and it was pretty easy and inexpensive. Maybe not as perfect as a professional version but I have been happy for about 10 years with it.
All you need to do is measure the width for the mounting locations, then buy the hardware (bows, mounts, etc). Next you assemble the hardware on a sheet of plywood at home and fit it all up from there. Go to the Sailrite website and they give awesome instructions on how to build your own. That is how I did mine.