First Mio's bass went off the charts, and now the headphones she happened to wear in episode 5 have started selling out of shops completely. The headphones in question, the AKG K701, are high-end headphones, retailing for 79,800 yen ($790), and so shop owners must be more than delighted to be pushing these high-end goods with speed.
We really can't underestimate the power of the otaku: the ones willing to buy just about anything revolving around the series of their obsession, even going so far as to rent hotel rooms in Saitama, the prefecture showing the second season of Haruhi first. So, for some reason, they're buying up the goods associated with their latest obsession: Mio.
I wonder if KyoAni is getting paid for product placement? Their shows have certainly driven traffic to Washinomiya thanks to Lucky Star, and we can already see the marketing power K-On has had. I'm not faulting them for it, since it's never really been blatant and out of place