Primary value is in copper, there is a huge-heavy transformer inside. There are several switches and a couple of overloads that contain silver electrical contacts. You will have to unscrew the switches and disassemble (smash) them to get at the contacts.
When salvaging microwaves, I usually flatten out the outer steel casing, clip out all wire, grab the Xformer, and all the little switches. I then use the cooking area to hold small steel scraps. when I get a thousand lbs or more of steel I sell it at the local scrap yard: currently $190 ton for low grade (appliance) steel.
If you find a good working microwave I would do the following: Donate it to a local charity, Salvation Army, whatever. You can get a tax credit for it.
Secondly, an outdoor microwave is great for melting metal and a whole host of other fun but insane experiments. Ever microwave a hole egg? A computer CD?