The price of Beats Mixr headphones in the United States from the Offical Beats by Dr. Dre website are $249.95. Taxes vary depending on where you live.
Note: Prices may vary in different countries. Not all models available in all countries.
No, Beats by Dr. Dre Mixr are not available in Australia.
Beats by Dr. Dre Mixr headphones have already been released in select countries, below is a link to them.
David Guetta's Beats by Dr. Dre headphones are called Beats by Dr. Dre Mixr headphones. I have provided a link to them below this answer.
Yes
Looks like on the ear to me, hence the lower price than the studios
The boxes for Beats by Dr. Dre headphones are fairly big. I have a pair of Beats by Dr. Dre Mixr headphones and the box is 17.2 cm X 23 cm X 11.8 cm = 6.8 in X 9.1 in X 4.7 in. I think all the boxes are around this size.
On-ear headphones - Mixr, Pro, Studio, Wireless, Solo HD, executives In-ear headphones - Heartbeats, powerbeats, tour, ubeats
It´s 15$
They are almost certainly fake or broken for that price.
Beats by Dr. Dre Wireless are the wireless Beats by Dr. Dre, below is a link to them.
Beats by Dr. Dre is a line of headphones.
Beats by Dr. Dre Solos are the smallest over ear headphones by Beats by Dr. Dre.