J&R offers the Panasonic LUMIX G 20mm f/1.7 Micro Four Thirds Lens
, model no. H-H020, for $319.99. Coupon code "CES2013" cuts it to $309.99
. J&R Rewards members receive free shipping
. (If you're not already a member, click here
to join; it's free.) That's the lowest total price we could find by $37. It's compatible with Panasonic LUMIX G cameras.
Update: Note that this item is temporarily out of stock, but can still be ordered at this price for delivery when available.