That's the problem I don't have any spare cables..
That's silly. They're cheap enough and it's essential unless you're just a hobby player. What happens when you break it? Say the drummer drops a cymbal on it and slices it in half. Or you trip over it and the end gets torn off.
Cheap cables (and expensive Monster "bass" cables) also attenuate the high frequencies from your instrument. A cheapie might be OK as a backup but it's wise to invest in a good quality instrument cable.