Some cosplayers make their own costumes. Some buy them. The price range for costumes can go from affordable to totally not.
The costume you are looking at costs ¥98,650 (US$1,172). It's the duds for "Purple Heart", the goddess version of Neptune, the main character of role-playing game Neptune.
The game is a send-up of the game industry, complete with goddess characters that represent game consoles. The goddesses battle the evil "Majekonnu", a Japanese word play on R4 carts.
In the costume, that's Rie Tanaka, who voices Neptune and Purple Heart. She also not only has voice credits in Phantasy Star Portable and Shin Megami Tensei: Portable 3, but also her own trading cards.