Hey now - lets just think about this for a minute - you may scoff, but there are far more uses to this than you might think, so it's not such a crazy thing. It's no different than selling filler powders used in epoxy resins to reduce shrinkage, cracking and to increase the viscosity of it.
I keep a margerine tub of slate dust for exactly this purpose - and I regularly use talcum powder mixed with CA as a spot filler which goes rock hard in seconds.
Mix with a little acrylic medium, a smidge of dye and you have an excellent grain filler to rub in.
Going camping? (or have a yacht that requires a ditch bag) grab a few handfuls and mix with that old crappy oil based paint that's been sitting in the back of your shed for 5 years and press into a tealight mould to make firestarters that will ensure even damp wood will take, and last longer than a tealight for a small camping stove, that uses hexamine bricks.
Oil spill? obvious. Same for paint / varnish / whatever.
Plus, if you are thinking of disposing of said cans of paint - bung a load of sawdust into it, mix up until it's a paste and leave it open until it sets - then you don't have to worry about taking it to the dump to be "disposed of properly" as it's now essentially inert.
Regardles of the price, the usefullness of this tub of sawdust shouldn't be disregarded quite so quickly.