The Apple Store online has refurbished 1.6ghz models for $999. Comes with a 1 year warranty and you can get the extended 3yr Apple Care warranty on it as well. I bought one of these when they first came out for $1800 so $999 is a pretty good deal.

I would really advise getting the new version or getting the new Macbook instead (which I also got when they first came out). The performance on the new version is much much better than the first gen Air. Its actually similar to the performance of the regular Macbook, especially if you get the SSD. But by then you're looking at $2500.

If you work for a big company or federal government or in education, you can also get a small discount if buying directly from Apple. Otherwise Amazon is usually a better deal as you can avoid taxes in most places and get free shipping.