If you purchase a Code Alarm off eBay, make sure you are buying a complete alarm. The newer, low end Code Alarm stuff is all modular. You will need the base module (CA-425 I believe) and then whatever added feature modules you would like (keyless entry, 2way, remote start, etc). It looks cheap (most modules are around $30-40 shipped) but when you add all the features you want its cheaper to buy an all-in-one unit.

**Shamless Plug** I have a CA-670 2way for sale in the For Sale forum /**Shameless Plug**