How would i go about getting a remote for a van?

The remote you want is called a "key-less entry" remote. No you do not have to buy the whole system. The remotes can be bought from a GM dealer or off of the internet. After you get the remote it will need to be "synced" with your van's key-less entry system. You should get the directions from who ever you buy it from. Normally the GM parts department will do the sync for you when you buy the remote.