networking with usb/serial/other

so one of the pcs im setting up in my newfound renderfarm does not have a nic, i now i could go out and get one but the idea is to set up these computers on an insane budget of $10 and i already used $3 on a case and still need a couple of other parts [cord, hub whatnots] so is there any other way to integrate this pc into the other two with usb or serial port; i found this one program called FIREHOSE
“FIREHOSE gives you a basic data transfer over multiple network devices supporting TCP/IP layers. Stripe multiple 100Mbit, Gigabit, 10 Gigabit, or firewire to give one humungous pipe for firehosing your gigabytes and gigabytes of data.”
i can get all kinds of wires at Goodwil computer works shoppe for super cheap [how i got the $3 case] so any help with this would be greatly appreciated

ps i dont have fire wire either. all it has is 2 serial ports and two usb 1.0

a network card shouldn’t cost more than $1 second hand, even get one donated.

Alltaken

yeah then you could just buy two cheap network cables, make them crossover and then bridge the connections, i think.