1. Thrift Stores and Consignment Shops: Local thrift stores, consignment shops, and second-hand stores are excellent places to discover unique and pre-loved items. You can find anything from clothing and accessories to home decor and vintage collectibles.

2. Garage Sales and Estate Sales: Garage sales and estate sales can yield a variety of items at lower prices. You might come across valuable antiques, electronics, furniture, and more that you can resell online.

3. Flea Markets and Swap Meets: Flea markets and swap meets are treasure troves of items from different sellers. You can negotiate prices and often find a wide range of products, from handmade crafts to vintage goods.

4. Online Auctions: Participate in online auctions on platforms like eBay, DealDash, and ShopGoodwill. These auctions can provide access to a diverse array of items, often at competitive prices.

5. Online Marketplaces: Explore online marketplaces like Alibaba, AliExpress, and DHgate for sourcing new items directly from manufacturers and suppliers. This can be a great option for purchasing products in bulk.

6. Clearance and Overstock Sales: Retail stores often have clearance and overstock sections where you can find brand-new items at significantly discounted prices. These items can be resold at a profit on your online platform.

7. Closeout Sales: Similar to clearance sales, closeout sales happen when a retailer is closing its doors. You might find bulk quantities of products at deeply discounted rates.

8. Social Media Marketplaces: Platforms like Facebook Marketplace, Craigslist, and local buy/sell/trade groups on social media can connect you with individuals looking to sell their items directly to local buyers.

9. Liquidation Auctions: Liquidation auctions can be a source of surplus or returned merchandise from various retailers. Websites like B-Stock Solutions and Liquidation.com offer access to these auctions.

10. Wholesalers and Distributors: Contact wholesalers and distributors in your niche to explore the possibility of purchasing items in bulk at wholesale prices.

11. Craft Fairs and Artisan Markets: Craft fairs and artisan markets can be a great place to find handmade and unique items that you can resell online to a broader audience.

12. Local Manufacturers and Artisans: Connect with local manufacturers and artisans to source handmade or locally-produced goods that have a distinct appeal.

13. Online Wholesale Platforms: Platforms like Alibaba, SaleHoo, and Worldwide Brands offer directories of verified wholesalers and drop shippers in various industries.

14. Network with Other Sellers: Establish connections with fellow online sellers who might be willing to share sourcing tips and potential suppliers.