You could try Tesco. I got a Linksys wireless ADSL router but they also had a cable version. That was about 7mths ago and it cost £55, believe they are now around the £40 mark.
I got one you can have, never used Netgear WGR614 wireless router… lost the instruction book though but should still be ok. Tenner plus p&p. No use to me as I’ve got adsl.
Mark ive got one kicking about the house i dont use any more due to wireless i used it with NTL in the past and it was great, not sure where the power supply is sinc ei moved recently but its yours if you want to cover postage and i can find it!!!.