I'm no expert on art. I'm not one to judge someone who pays thousands of dollars for a only slightly changed canvas, but I'm not sure why anyone would want to. $10,000 is already a huge amount of money on its own, so in no way is a "black dot on a white canvas" worth that kind of money. Like Entity said, you can make it on your own for much much cheaper. Hell, you could just do it on MS paint or Paint.NET or something absolutely free and call it good.
When I went to New York in the summer of 2009 (I think), I visited the Metropolitan Museum of Art and saw this:

(No, I did not photoshop this. This thing really is hanging in that museum)
I think it's questionable that the single biggest art museum in America has something like this hanging up in it. It has virtually nothing to it. Art is supposed to convey a meaning, and something like this really can't convey anything because there's... well, virtually nothing to it. Whether art has a meaning or not doesn't make a difference if there's nothing to get that point across. Something like this is probably only worth about $50, simply because, anyone can buy a blue canvas and cut it into a parallelogram shape.
Again, if you want to pay a ton of money for this sort of thing, fine, but I don't really find overly minimalist stuff like this to be worth much.
I need a shot again, that sweet adrenaline.