I've been looking for dd-wrt routers and this looks quite cheap. I'm not sure if it is the b1 or the lesser v1 but still cannot be all bad can it???
Please note: This is just a router, not a cable or adsl modem router.
Update: Sorry, I listed as an n31u and its an n13u, sorry for any confusion.
UPDATE: Thanks to @thefinest1 for finding it cheaper
http://www.ebay.co.uk/itm/ASUS-N-RT-N13-WIRELESS-ROUTER-/330730918785?pt=UK_Computing_Wireless_Access_Points&hash=item4d01195381 - £20.98 - (18.99+1.99)
Sold out from ccl but the Argos link has over 10 available.
PLEASE NOTE: Argos one does not have USB as stated by moosery2
another DD-WRT compatible router on eBay with a warranty