Keep in mind that remote start alarms are much less secure in the way of immobilisation than any other alarm. Remote start is cool, and it makes noise, but if an experienced thief wants your car they won't have a hard time bypassing it.
If you're after it for security, you're best off getting a black wired two (or more) point immobiliser/alarm.
But if anyone wants your car that badly there's nothing stopping them from putting it on a tilt tray and towing it away.
Another thing to look at when you're buying cheap shit off ebay is how long it will last. I bought my alarm off ebay a while back and the one button on the remote is almost worn out, I can't find new remotes for sale anywhere, and one of the relays in the alarm module is a bit dicky.