I got 3 machines in a lan and I don't leave any of them on all the time. and I work on all 3 machines in different times.

it's kinda a pain in the *** to keep files in one system and then have to turn on a particular system to get the file.

is there anything that is small and cheap that will plug into my router (always on) RJ45 that act as a netowork storage drive?

so I can access my files for all 3 machines whenever I use it?
100-200 megs should be fine.