In commodity markets, it is supply and demand. In niche markets like "high end" computer cases, it's a variation on market pricing. If enough people wouldn't pay what they are asking, the price would come down - or if they couldn't afford to sell the case at a cheaper price, they would go OOB. You have to be very careful with your production when you play the edges. I would bet that Lian Li doesn't make as many cases on an annual basis as many would think that they do. And all those on-line shops that seem to carry them don't stock very deep and sometimes don't keep any inventory at all - a lot of it is "just in time" or drop-ship.
.bh.