Well, let's see.
To the average guy, the barrel, being used and nonchrome lined, would be worth $90-$100. An early M16 freak MIGHT be willing to go a lttle higher.
Three prong suppressor: $5
Complete stock/HG assy: $25
Early Air Force contract M16 (NOT M16A1) smoothside upper, if complete, $100 if it's in perfect shape, w/99.9% original finish.
I base these estimates on what I paid vendors for the same pieces about a year ago, both at gun shows, and off the EE section of this site. My barrel, though, was a brand new C MP C type, with a chromed chamber. It came w/everything, including handguards, except the gas tube, and cost me $105. My value estimate on yours deducts for the used status, but adds back in for the earliness factor.
Obviously, these prices are "off the top of my head" estimates. The increasing interest in building early type clones may be an upward factor, but the increasing availability of this early stuff may be a downward value issue.