There was a guy on here that sold them but I can't remember his username. I used one for most of last season but it interfered with flying my planes so I took it off. I had to reduce total throws so there wouldn't be any binding "in the corners". Expo has nothing to do with what a cyclic limiter does.
A swashplate can only tilt so far. If you max out the tilt in both directions individually, when you command max in both directions it causes binding. There are many methods to set one up. Just try to get even amounts of throw in cyclic that is just short of binding when both aileron and elevator are at their max.
Matt