I bought a mint G version from KEH for $450 ish last year. It was mint, box and all. It wasn't a deal, just a fair value. I also bought a (new) Sigma 105 OS) macro F2.8 for $7xx from B&H. I think you should look at the real market before you throw out a price.
The lens market is not like the body market, as you still have options for new.