The number of times you can propose a 'bid' depends upon your subscription plan. As a creator, you should subscribe to the membership plans. By doing so you get an assortment of benefits which includes enhanced visibility and ways to grow your business. You can add product categories, win bidding opportunities and be a part of all the 'icustommadeit' facilities by signing up for the subscription plans!
You can know more about bidding opportunities and subscription plans, click here.