Filetransfter over patch cables? How old are those laptops really, if you had to use cables instead of wireless connection to the router, those stuff should go into the junk.
External HDDs are rediculously cheap, I have one for a while and it was a "lifesaver" already a few times. Payed less than 100€ for 1Tb 2.5 inch drive back then - IMO a better investment than buying two fullpriced endless mobrespawn grinders.
There is one more option for backups - a cloud site. Most of them are not free, but some do give you a certain amount of space for free upon registering (for example 50Mb on rghost.net). I'm not using that option because I don't really need it plus the whole cloud idea stinks like smartphones.