I'd definitely take offers on Greek Twilight. I personally think she'd be in the $150-250 range. After the MOC Greek flood, the unicorns (Glory, Moondancer, Twilight, Sunbeam) don't pop up for sale very often. They are usually pretty sought after & I'm sure you would have multiple people interested if you decided to sell her.
If I remember correctly, the MOC Greek flood was due to a warehouse find of "old stock". There were 2 or 3 sellers that sold them back in the day. New MOC/MIP Greek stuff pops up from time to time, but never in the quantity from way back when.