I have been seeing some people who possess sites making $1/day. Now most of them have different price ranges as they may be quality sites or just plain old proxies. So how much is an average $1/day adsense site worth?

In general, I think you can value companies by 3-5 times their annual income. However, I think that I'd have a hard time paying $1000-$2000 for a site made specifically for AdSense.

I would go with 3 x, but remember some sites have only been up for less than a year they are selling before traffic drops.