i play electric guitar so already own 2 amplifiers...if i buy a bass guitar will i have to buy a bass amp or is it possible to play it through my existing amps or will it damage them?

Blinx,
I've played a Gibson Les Paul guitar and a Fender bass through the same amp (on the same night, matter of fact), and everything went fine. Granted, it was a cheap little Peavey amp, and you may want to check the specifications on an amp-by-amp basis, and you also may want to get a lower-end amp strictly for the bass.

But I think the short answer to your question is yes, it should work for either instrument.