One great way to see different merchandise suppliers in one location is by attending wholesale merchandise trade shows.  There are shows in cities across the country, and there will definitely be one near you within the next year.  At a show, you'll be able to see all of the merchandise and talk face-to-face with the wholesalers.  

The internet is another good place to compare wholesalers, but make sure you know who you are talking to.  Sometimes an impressive-looking site can be run by scam artists.  Check out the company and talk to salespeople there before you give them any money.  Make sure you're dealing with someone reputable.

Take a look at the companies linked to this page to get some ideas.

Important questions to ask are:
How long have you been in business?
Do you have other customers in my area?
How long will it take for me to receive my merchandise?
Are you a dropshipper?
How many different items do you carry?
Are you a direct importer?

If you choose wisely, you can dramatically improve your profits by finding better merchandise at better prices, which will keep your customers coming back again and again.  Choose your wholesale merchandise supplier wisely.