My sister has her late husbands, my brother-in-law's, relaoding equipment and I'm thinking on buying some of it, but we are not sure what everything is worth? He kept it all in real good shape.
hard to say. Got a list? How old is the stuff? Slightly old items from current manufacturers will bring more than (most) weird old stuff from the 50s and 60s. (There are exceptions to this.) Some of the older stuff is incompatible with current equipment.
Get a detailed list, and then go to Midwayusa.com, and check against their listed prices. Bear in mind that current prices for consumables will be unreasonably high.
His handloaded ammo, I would disassemble for components.