Get them hooked on cheap
Yeah, that's why Windows even became popular back in the late 1980's. All those apps with the OS on the desktop, 'free'. It wasn't free, but seemed so. The low price will get people to try the OS, that's a time-honored way of admitting you want people to change, so they will LATER buy the higher priced stuff, after becoming used to the OS.
Thus I too will do as you, and buy a copy (but of System Builder, which is 1/3rd the cost of what will become Win8 Pro retail). And then it will sit on the shelf. Nota Bene: if you want to buy a retail new copy of XP Pro today, it costs about $300. A company through Amazon was suddenly selling out its last five copies of that GENUINE retail version (replete with inventory control tab) for only $150, so I snapped up two copies. I believe $150 is what I paid for XP Pro when I first got it at Sam's Club, back in 2006. The just-purchased ones have the same blue-and-orange retail packaging, holographic disk, etc.
So yeah an INVESTMENT deal, if a good OS long-term, as it will keep its value.
