I wouldn't go too cheap. Spend at least $50 on it and don't buy belkin as they are crap. Look at Asus, Netgear, Dlink, or Tplink. How far away will you be from the router?
If gigabit speeds ain't your thing and you don't need IPv6 then the WRT54GL would be the ticket. I have had the WRT54GL since circa 2006 and it's been soild ever sense. No rebooting or any of that crap. I even flashed with DD-WRT. Plan on upgrading maybe this summer though. I don't need gigabit speeds however. I just want the IPv6 capability.