Well, lets round things off a bit.
There are about 100 - 200 mg / ft square of silver in paper and about 300 mg / ft square of silver in film.
Go figure the capacity of your fixer and the amount of material put through it and you can guesstimate the amount of silver in exhausted fixer. Now, figure that the extraction process from the fixer is going to cost you, and then that the extraction and refinement of the silver from the material used to extract silver from the fixer (2 step process - yours and then the refiner). This reduces the value of silver by over 2/3 in some cases.
Now, you can figure what your silver is worth!
Ain't much, is it?