17-40mm L

I'm wondering how much I should spend on a used one. Within the past month, I've seen prices from 500$ to 700$. I thought maybe it was related to date code or condition, but there seems to be no correlation. It is 728.09$ new on amazon. Also do you think it's worth buying new for the one year warranty?

They seem to sell for about $600 in good used condition on the forum boards here. Adorama has refurbs for $670, and they include a one year warranty. As for whether the added cost of buying new/refurbed for the warranty is worth it... Totally up to you.

$60 depreciation for Used + $30 per year depreciation + some condition adjustment.
so 1yr/2yr/3yr old excellent condition around $620/$590/$560 respectively and so on.
Good thing about buying used, you can resell for almost same value. It has its risk too.