Hey RW,
Out of the box is hard to determine. You can get out of the box systems that range from 1000 bucks to 3000 bucks or more. This system I put together will cost you right around 300 to 350 give to take. I only used 75 feet of weighted tubing so my system was a little less. Weighted tubing is expensive but man it's awesome and makes life easy when it comes to this type of setup! Keep in mindy if you bought this system out of the box from a retailer if would be about 600 bucks I bet as you know as well as I do they are going to make their profit as well. Here is a quick breakdown of what I spent. I also think Joker posted his cost too earlier in this post.
Eco 7 pump = 105 bucks
75 feet weighted tubing. 117 bucks.
3 , 9 inch round diffusers fine bubble. 50 bucks.
PVC pipe for air system about 15 bucks.
Cat kennel to house air pump. 20 bucks.
Hope this helps.
