How long can you buy ethernet cables for ps3?

May be...

i need a pretty long one

till your desire

Ethernet cables can carry a signal quite well over long distances. USB is much more limited. You can get by with up to around 300 feet if you use a good quality Cat6 cable.

they make really long ones. go to best buy or some other electronic stores. I just bought mine and it was 25 feet. i think there were others that were longer.

You don't need a brand name cable, any cable will do. The longest i have is 30m. (98.4ft).

300 feet