Guidance on selling heavy equipment

We are in the process of cleaning out my father-in-law's barn after his passing. The barn includes farm equipment (tools and machinery) from 70 years of farming, as well as construction equipment from 40 years of corporate construction jobs (boxes and boxes of screws, building tools, etc), and heavy equipment used for excavating. We are at a loss as to where to begin to find fair pricing to know how much to ask, as well as where to sell the items that won't cost us a fortune in advertising or shipping fees. Any advice would be greatly appreciated!