The definition of compliant is obeying. An example of compliant used as an adjective is a compliant student which means a student who follows all of the rules. complying or tending to comply; yielding; submissive.
We're having the ring bearer wear a tux that is age appropriate. It costs about $70, everything included. Your tux shop should have these or be able to order them. Edited to add: A friend several years ago had a ring bearer in her wedding and dressed him in a shirt and tie instead of a tux.
In most cases you can find a traditional tux for less than $200. A name brand tuxedo such as an Armani tux will cost up to $1,000 to rent when you can buy the suit for around $2,000. If you wear the tuxedo twice you have more than made up for the cost of buying it. In addition, you do have the option of buying just the pants and jacket.