Establish Customer Relationships
Hands down, the best way to locate antiques to sell in your retail antique store is to purchase them directly from customers. People will oftentimes bring in unique, old items in hopes of identifying and/or selling them. If you think there's a good chance customers in your store would purchase it, then go ahead and try to purchase it. Just remember to purchase it at a low enough price so you can make a profit off the transaction; otherwise, you'll end up wasting your store's money and space.
As you begin to purchase products off of your store's customers, they will likely spread the word about your business; therefore, bringing more customers into your store. While some of these customers are there simply to purchase items, others might try to sell their own antiques to you. Always take the time to inspect each and every antique offered by a customer, as you never know just how valuable it will be.
Auction Websites
Another excellent outlet for locating antique items to sell in your retain store are auction websites such as eBay. You can literally find just about any product or item under the sun using eBay, but it's especially useful for locating antique and vintage items. When people don't know where or how to sell an antique item, they simply place it up for sale on eBay and let buyers set the price. As an antique store owner, you can use this to your advantage by locating products here. After you've received the products, you can then sell them in your store.
Yard Sales
Yet another excellent method for locating antique products for your store is through yard sales. If you live in or around a large city, spend a weekend afternoon driving around and checking out yard sales. Depending on your luck, you might come away with some amazing antique items at incredibly low prices.