Unless every tool in there is marked Snap-on, Cornwell, Mac, or Wright, I think you would be hard pressed to part it all out and make that on those tools.
From your pictures, there looks to be a mix of many different brands in that box. Most of the value is in the box itself. I have no idea what one like it would cost, but probably in the 700-1000 range for the box. I don't shop Sears, so no idea what comparable box they have or a retail price.
Personally, if what your pictures show is all that is in there, I would sell it for the $2800. I really don't see that many high-end tools to be had.
Others may chime in, but that is my .02 worth of opinion.