You could also do something unique and sentimental for your bridesmaids and make their gifts yourself. It's not necessary to spend a lot to create popular looks yourself. Best of all, you are in control of the cost of materials, you can pick from Swarovski crystals and pearls or common materials found in most craft stores. There are many jewelry making kits at big box stores that will get you started. You can make beautiful earrings, necklaces, bracelets, anklets, beaded belts, and anything else you can think of!
You'll want to keep in mind that you are trying to make something that can be incorporated into her everyday wear, as well as, match each individuals jewelry personality. For example, gifting an overly-embellished statement necklace to your girlfriend that tends to be a minimalist, probably isn't a mindful decision.
Your bridesmaids are those friends and family you've chosen to stand by you on the most important day of your life. So whether you go all out on expensive crystals and pearls or simple, elegant costume jewelry, the most important thing is a thank you to show them how special they really are to you.