Well, if it has to be a Linksys WRT54G 54Mbps Wireless-G Cable/DSL Broadband Router than Outpost(Fry's) has it for $39.99 w/free shipping.
I prefer, and use, the NETGEAR WGR614 Cable/DSL 54 Mbps Wireless Router, 802.11g for ease of use and NO problems.
Check Best Buy - $39.99 w/ free shipping too.
(search for WGR614)
That's just me though