I guess I should bust out with some options now.
For the windows module. Which allows you to lower and higher your windows from your remote control is $94 each. Now each module operates two windows. So you need 2 modules for all four windows if you wish to do all four windows. It is popular for people to do just the front two windows.
We also offer a backup battery module which is $50. This prevents thieves from cutting your battery cables to kill the alarm. The backup battery is hidden and allows the siren to run with a backup source of power!
The trunk pop option is $30 and it allows you to push a button and your trunk to pop up. (pretty self-explanatory I know)
A Piezo Siren allows you to have an extremely loud siren and a backup siren. Which is $30.
The siren w/backup battery is popular and it comes with a 6 tone siren. It is by Revenger.
Windows Module = $94 ( 1 for 2windows, 2 for 4 windows)
Backup Battery = $50
Trunk Pop = $30
Piezo Siren = $20
Siren w/backup battery = $75
Those are my recommended options. The following is the options you can get with your alarm that would be nice to have but you really do not need them.
The Proximity Sensor $87 which allows basically you to leave your windows down without fear of people reaching in your car. It develops a field within your car so if you break that field the alarm goes off.
Another custom little tidbit you can do to your alarm is add a voice module. It is $100 and comes with 19 different voice messages.
-Jason
More Information from the Viper Website on these products! 
