Hi,
You might want to think about what exactly you are looking for in your computer: form factor? battery life? expected usage?
There are a lot of different kinds of Macs, new and used, that $1000 can buy. Perhaps all you need is the current Mac Air 11.6'' You can buy that new in its stock configuration and have money left over. Perhaps you want to hunt for an older rMPB. It is certainly possible to find that for $1000 USD as well.
Even though Apple only releases a few models every year, there is not a "one size fits all" device. If you are simply looking for a basic machine that you can use to check facebook and browse the Net, you could do worse then buy a Macbook from 2011-2012 and saving yourself a few hundred dollars. Only issue there might be battery life if the machine has been put through its paces.