It is worth what the market will bear. What you need to know is the condition of the equipment and if it is operational. Make a low ball offer like $250 and work up from there. I would think from doing a little research my self that that set up is about $400-500. You also need to consider, is it going to need a CLA?
The Mamiya C equipment ranges over a 40 year production period. The 55mm is going to be a Seiko shutter lens. The 80mm could be any of five versions. If it is contemporaneous with the C330 then a Seiko shutter would be normal. The 180mm could be a chrome Seikosha shutter model, or the Seiko shuttered plain 180 or the 180mm Super. I would not pay a lot for the chrome Seikosha shutter lenses. The Mamiya grips vary a lot in type. The pricing suggestions seem reasonable for fully functional items.
It is worth what the market will bear. What you need to know is the condition of the equipment and if it is operational. Make a low ball offer like $250 and work up from there. I would think from doing a little research my self that that set up is about $400-500. You also need to consider, is it going to need a CLA?