Remote unlock for 1990 300zx

Anybody have suggestions as to how to add a remote transmitter system to lock/unlock the doors for a 1990 300zx. An alarm would be a plus but not required. Thanks in advance.

Craig

there are a couple different options. How much are you wanting to spend?

I'd like to spend between 100-150.
cd

I saw a product not to long ago that had a box just like that of a alarm but when you walked away from you car it would lock and when you got so close it would unlock. I can't remember how much it was but that would be kind of cool. I'll see if I can find it again.