[Speedslug]

That's going to be a "go with your gut" thing I'm afraid.

Look up the prices on any of the larger quantities to get feel for where current numbers are and weight most of it so you don't shoot yourself in the foot with under estimating how much you are thinking of off loading.

Then write down a number and sleep on it for a day or two.

If it still feels go, do it.
If it doesn't then you will want rethink the actual details and do the long math homework and go with the numbers that that gives you.

You will sleep better months from now knowing you did the due diligence and did not take advantage of a friend but did not throw away an investment either.