While your question is more one of how can you make a buck off 300
lbs. of dull end mills, I for one will choose a reground end mill most
of the time. I have several reasons for this.

If I am milling on the edge of a piece of material it makes no
difference to me if the end mill is .005 undersize.

If I am milling a pocket or milling a surface being a little smaller
makes no difference either.

If I am milling a slot, an end mill tends to walk a bit so the slot
becomes a little bit wider, an undersize end mill will often allow me
to take a larger cut and keep the slot from widening too much. Also,
when I finish the slot to size, I only have one side rubbing, so it is
easier to get a better finish and predict the behavior of the cutter.

So unless the price of a new one is more than sharpening go for the
regrind. Usually however the tool grinding shop will beat replacement
every time.

Iggy, you might find a sharpener in your area that will either take
the dull ones off your hands with no effort or give you a deal on bulk
sharpening. I worked for a tool and die maker that had a fixture to
dress the end but usually he would just collect a dozen before he
would drop them off at the sharpener. Of course the economics may
have changed since then, but I suspect that a good quality end mill is
most always worth sharpening.

Roger Shoaf

Ignoramus6607 wrote:
Someone is offering me a lot of appx. 300 lbs of used HSS endmills,
which are neatly sorted by size and need resharpening, for $75.

Let's say that I had an end mill sharpener like a Darex V90 or
whatever. Realistically, how long does it take to resharpen an end
mill (I would hire someone) and how much can I get per dozen of
"professionally" sharpened end mills, say in 1/4" size.

i