Not trying to price cap at all, just trying to help out.
1. Is this key from a MY06 - 07 IS? Or a MY 2008+?
2. Has this key already been programmed? (Since you said it was your spare key, then it most likely has)
3. If you don't know 1 or 2, check out this FAQ thread: http://www.clublexus.com/forums/is-s...t-key-faq.html
4. Used keys are selling way below your asking price. Check both here and your local Craigslist for details.
Good luck with sale!