The diameter of that skimmer is greater than 18" and it's CAST acrylic. I used extruded's cost because it was the first result I could get a solid number on
Personally, I find it's more an issue of how much a given sum of money is really worth to a person. There's a lot of people out there who don't work for their money (eg. investors, business owners, ummm, shadier types, etc). To those people, $9k isn't a function of how many hours they spend to earn it, it's a matter of how good their portfolio is. Big difference in the "value" of money there.