So, are you looking for something with a siren to hopefully scare somebody off or are you looking for something that will give you notification also?
If you're in an apartment, you'd want to go wireless I would think but be aware that you still must provide power to the panel through a transformer. The siren will have to be hard-wired as they are not available wireless. If you want notification, the least expensive IMO would be to add-on the Envisalink board and that must have a network connection to your router.
Hey, and I want everyone to know that I too am not pushing anyone's products for any reason other than I am familiar with them. I am not in the alarm business. It is a casual hobby of mine in that I know some stuff but by no means am I proficient at any of it.
So, based on my familiarity with DSC systems, you might want to look at this.
http://www.homesecuritystore.com/p-1456-kit32-16cp01-dsc-power-1832-security-kit-with-rf-keypad.aspx $149.50
You will need to add a wireless motion to that kit. And you'd be into it for another $99 for the Envisalink board if you want notification.
http://www.homesecuritystore.com/p-...-alert-module-for-dsc-honeywell-security.aspx
You could add in other wireless components too as you desire.
Do not order this without doing your homework. I am not well versed enough to recommend this system without that warning. Also look at the manual for the product. Programming is not truly difficult but virtually everyone that has programmed their own said they had to read the manual through like three times paying very close attention. The manuals are written for professional installers, not average Joe's. If you read it and study it, eventually it will "click" with you. It's not intuitive though.