Costuming rules for children's divisions have become extremely strict. Rhinestones are certainly out, and even some fabric types can get you in trouble.

Dress4Dance offers by the rule costumes for boys and girls. You can call (609)638-8533 or contact them through info@Dress4Dance.com

Sorry, I did forget to ask what association the competition your son will be dancing at is affiliated with.

Here are the rules for USA Dance
http://www.usadance.org/forms-and-resources/0yaowpubix/

NDCA Rules are:
http://www.ndca.org/news-and-resources/resources/69qskjrtwl/

Andrew Smart's, World Promotion Competitions - one day events are less on strict rules and more on fun. I've seen lots of little girls in sequined costumes. And boy does Andrew like to let everone know he WILL play AC/DC music in the Latin heats. His goal is to encourage more children to dance so All children's heats are FREE. They still have to pay to get into the ballroom as well as for the lunch & dinner.

This does not help answer your question but if anyone can help her, I have a 9 year old grand-daugher who would also be interested. A partner would be nice also if anyone has young boys looking for a partner.