Apple’s latest model AirPort Extreme and 2TB AirPort Time Capsules are available as discounted refurbished units in Apple’s online store.
Unfortunately it seems you’ll have to wait a bit longer if you were hoping to get the newer-model 3 TB Time Capsule at a discounted price. While refurb models of the old version are available, the new version with 802.11ac support is nowhere to be found for the time being.
The refurbished AirPort Extreme is priced at $169, and a refurbished 2TB AirPort Time Capsule can be had for $255.
The refurbished units are available in Apple’s online store here.