i was plugging cheap...
you can get a nic at compusa for 19 bucks, (need two)
and then can get a cable made from a techie shop (i hate making cables) for about 10-20
for 24 each, you can get a netgear fa311 (10/100) which is some serious speed for a serious budget.

(i have two netgear FA311 nics in my server, works great, especially at full duplex with my FS105 5 port switch...)(one for cable modem, other for network)