Not Displaying Price for certain products

My intention of using the Marketplace plugin was not really to sell anything online, but rather to create an SEO rich listing of various products and services.

As such, i don't want to display price for the products to the website visitor but rather ask him to 'call for best pricing & availability'.

I see that the 'price' is a mandatory field when saving a product.
How can i go about removing this option?