You can buy dancewear from www.nydancewear.com by sending them money orders, and you could have it shipped, in a plain box with NO identifiers, to a post office box at one of those places like Mail Boxes, etc. (The US post office box will not accept shipments from UPS, FedEx, etc.).  Your parents may question a plain box that arrives for you at your house.

HOWEVER, I think the best way for you to get your dancebelt, tights and ballet slippers is by joining a dance class and devoting your eforts to learning dance.  Tell you parents you want to learn ballet. (It may help to read up on ballet at your library first, and prepare the reasons why you want to take ballet class.)

Some parents are reluctant to allow their boys to take ballet, but stick to your guns!  It's great exercise and helps develop your body.  Focus on the class work, learn your ballet exercises, and become a danseur!

Before long, your parents will come to accept your desires to ballet.  Then you can expand your dancewear, too.

Good luck!  BalletMaster