There's really no such thing as a park binding. In fact, the high end FKS 180 is basically a race binding with a different paint job. Keep your search simple, or you will get confused. The more you spend on a binding, the higher the DIN gets (which might be a bad thing for you given your weight, which is why you need to find out your specific DIN), the more metal is in the construction, and the more the binding favors retention rather than release.
The cost of a binding is based on those factors, and the presence or absence of those factors is what makes a price go up or down.