transferring files between 2 PC’s

i would like to transfer a bunch of files between my laptop and my PC without spending too much money… (anything over 50bucks), is there a easy way to transfer the files? and what are the steps? i have a nic card on my laptop (source) and could buy a cheap nic card for my desktop…dont realy care much about speed, i could leave it overnite to transfer the files… any advice? thanks