Your suit is a part of your image. Wearing a sharp looking suit gets you more bargaining power and adds to your image which can help you earn much more than you would spend on your suit. 
A not so good suit could lower your image and put you in a weaker negotiating position. Don't be suprised that people with think that you will settle for less just because of you suit. 
So replace them as soon and possible and you will feel proud of yourself when you meet others.