When you go to an accessory shop and ask for an alarm, what do they sell you exactly?

Does a basic alarm system like those that costs 2-3K comes only with the remotes, siren, alarm brain, LED indicator and sensitivity potentiometer?

Often sinasabi kasi nila na "wala pang power locks yan ser"...

What if my car already has power locks (stock), can that alarm system control the lock/unlock mode of my doors?

I'm asking this because I want a keyless remote lang talaga, so that I don't need to use my keys to lock/unlock my doors... I don't really care for the siren/alarm feature coz they're really pointless and annoying for me.

But the cost of keyless entry systems are almost the same as alarms, kaya I'm wondering which is a better choice.

Meron bang murang system where I can add a trunk popper as well?

Convenience lang talaga habol ko, hirap magbukas/sara ng doors/trunk pag may bitbit kang bata hehe