Great products at fair prices make the sale on eBay, so where do you get the goods? It's all about forging relationships with reliable, trustworthy suppliers.

The needs of your business will dictate what form these relationships take, but your choices include manufacturers, wholesale distributors, drop-ship companies, liquidators, closeout distributors, job lot traders and eBay itself.

Price and quality range dramatically among these providers, so it takes time and patience to find the best match. Attending trade shows and joining trade organizations related to the business you want to specialize in are great ways to meet potential vendors. These activities can also help you fine-tune your buying decisions. "This is what any retailer in America would do for information on trends and consumer buying habits," says Lisa Suttora, the Seattle-based founder and CEO of Whatdoisell.com, an online guide to successful sourcing.

Following sourcing strategies used by brick-and-mortar retailers makes good sense for eBay entrepreneurs, says Suttora. "You're not building an eBay business," she says. "You're building a retail business on eBay." Mimicking traditional retailers lends more credibility to eBay sellers and boosts repeat sales, Suttora adds.

Keeping up with business news can also guide your buying decisions. An article on the renewed popularity of knitting, for example, suggests potential success selling knitting needles, yarns, patterns and other accessories.

That method supports another sourcing tenet: Choose products based on what buyers want to buy, not what you want to sell. Jeremy Hanks, co-founder and CEO of Doba LLC, a product-sourcing and drop-shipping service provider in Orem, Utah, cites the example of his wife and her passion for scrapbooking. When she started selling scrapbooking supplies on eBay, the business didn't find much support. "It's so easy to stick with the hobby mentality," says Hanks, adding that in doing so, you skip the crucial step of assessing the strength of a particular market.

As a drop-shipper, Hanks notes that services like his help eBay sellers test a product without a huge investment upfront. His company charges a monthly or annual fee to access its inventory of 250,000 whole-sale products as well as pictures and product descriptions. Sellers pay for the product only when there's actually a sale. Doba's fees start at $30 a month. Drop-shippers in general charge fees of about $5 per shipment, a premium price that should be weighed against the value of not having to keep inventory, photograph products or write copy.

Markets and consumer tastes can change suddenly, so most eBay experts recommend staying alert to new sources, even when existing suppliers seem reliable. Arman Yavuz (eBay User ID: naras04), owner of Naras Technology LLC in Chicago, has established a solid customer base for his company's laptops and computer accessories. But strolling through a mall one day, Yavuz, 25, saw a buzz around a kiosk selling dog tag jewelry. Now he sells the tags on eBay along with a line of T-shirts printed with personal photographs. The T-shirts and jewelry gross up to $2,000 a month on eBay, while computer sales reach up to $70,000 monthly.

"We didn't want to concentrate on just one field," Yavuz says, "and there's an audience for pretty much everything on eBay."