Bridal party - What are you paying for?

I am planning a wedding for next summer and recently found out that my parents are wanting to help cover some of the financial burden. My parents were married in the late 80s and my dad’s parents paid for their groomsmen’s tuxedos and they paid for the bridesmaids dresses. In wedding I’ve attended, the girls purchased their dresses themselves. Since they are helping pay for our wedding, I want to respect their suggestion to pay but I feel they are underestimating the cost of these things. I am guessing it will cost us about $2,100 for this.

Edit to add: Planning on dresses from Azazie & providing each girl with earrings for the wedding. The tuxedos will be rented but we will provide ties, suspenders, and socks!