Curiouser and Curiouser

I'm beginning to think it's a good thing that I look at a whole bunch of stores online and spend my procrastination time shopping online (though I generally don't buy anything). I was looking at the Anthropologie website and decided to go into the sale section and look at swimsuits - because so many of their swimsuits are amazingly cute but out of my price range, especially because I don't really need a swimsuit. As I was browsing, I saw this suit:
It's a cute bathing suit. In fact, I like it a lot. And I had liked it a lot when I saw it a couple of days ago on the Urban Outfitters site. Except on the Anthropologie site it's about $100 cheaper because it's on sale. Of course, it's still out of my price range. I wonder about things like this - when the same thing is sold at different places for different prices - I pointed that out with two dresses from ModCloth and Forever 21 in a post a month or so ago. What really makes me wonder here is this: Urban Outfitters and Anthropologie are owned by the same company. How does this happen with such closely related stores?