There are both free and paid directories of suppliers on the market, and Worldwide Brands is one of the oldest and largest of the paid directories. Indeed, it was founded before AliExpress (or Alibaba.com) in 1999 by Chris Malta, an established eBay power seller, and has been trading ever since. Worldwide Brands has the largest list of suppliers and the by far the most products available at wholesale prices, but at $299 membership is very expensive, so it's worth asking what the alternatives are.
There are a lot of sites that list wholesalers, like eSources.com, and then there are marketplaces like Alibaba.com and AliExpress.com that sell goods from China at wholesale prices direct. Both of these are good free alternatives to any paid directory like WorldWide Brands.
Worldwide Brands is the largest and most expensive directory of suppliers, but it's not the only one. Doba is a reasonable service for finding suppliers that will drop ship direct to your customers, but only sells in single units and offers no wholesale or bulk goods. Membership is expensive at $29 a month.
Then there's Salehoo, which is a directory of both drop shippers and wholesalers like Worldwide Brands, but it's smaller and much less expensive to join, at only $67. Either of these are good alternatives to Worldwide Brands, but I'd recommend trying out the free alternatives first.