They've purchased the dresses you want them to wear, so it is important to be respectful of their budgets. One way to do this is to include pieces they probably already own. If black heels will go with their dresses, then let them wear the ones in their closets so they don't have to purchase new shoes. If you love pearls, then ask them to wear pearls in whatever style they already have. If one girl does not own them, faux pearls are relatively inexpensive to purchase. If, however, you are dying for them to wear a necklace that has your wedding colors in it, consider buying the piece for them. Many brides make these items part of their bridesmaids' gifts.
While navigating this challenging and stressful process, remember to strike a balance. Be considerate of their feelings while accomplishing the look you want. Dress your bridesmaids so they feel beautiful. Not only will they be grateful, but they'll love talking about your wedding for years to come!