Lol come on, even used... they cost much (and are high end) because they are durable :P... plus no one really fiddle inside or modify their high-end cans, so you can't really have a bad surprise.
If the gold lettering is still fully there I think it was really worth it! cMoy also cost about 30-50 so it's good for you, those portable amps does the job well enough I think.
Grado will always repair their headphone, it will cost you like 25 dollars, even out of warranty.
i guess I'll have to see about the grados once I receive them if the lettering is still intact. I already am getting a fiio e17 so I might sell the cmoy...