According to the blog of a headphones shop, AKG K701 was sold out for the first time since the opening of the shop. AKG K701 is a high class headphones and priced 74,900 yen (approx. $750). Mio wore the headphone in the episode 5 of "K-ON!".
Mio's lefty base guitar "Fender JB62/LH/3TS" was also sold out in 2-3 weeks and Fender Japan sent an order to the factory to produce the guitar in the amount of two-year sales.