Those are VERY nice things to provide to them already, and could be considered as a gift to them (i.e. minimizing their expenses by providing such staple items found at weddings). If it is in the budget - then go ahead and give them something unique that truly represents who they are as an individual or that you shared as friends (i.e. you and your Maid of Honor always ate Ice Cream on Friday nights during high school - give her a gift card to a local ice cream shop - minimal but worth it)...if it is not in the budget to provide more than what you already have provided, then I am sure your wedding party is already thankful that you have provided them their dress/shirt already. Good luck!