We all know women get paid less for their labor than men do. But a new study conducted on eBay finds that women get paid less for their iPads and vintage vinyl than men do, too. To add insult to injury, women tend to pay more for their purchases on eBay than men do as well.

When selling second-hand items, the differences between men and women were significant, but not huge: about three percent of the value of the item. The researchers, Tamar Kricheli-Katz, of Tel Aviv University, and Tali Regev, of the Interdisciplinary Center in Herzliya, Israel, analyzed more than a million transactions, though, so the chances are very good that that three percent is real, and not a fluke.

It was in the sale of new items that the numbers get ridiculous. In selling new items--those where there really can't be any question about the condition of the goods in question--women got paid 19.7 percent less, on average, than men. That's for selling the exact same item.

This naturally leads me to think about women-owned businesses. Are women getting paid less than a man would for completing the environmental remediation of an old parking lot? Are all those crafters on Etsy getting paid too little because they're women? Should the women who come here to Inc. to pitch me on their hot new communications device, rental service for tech gear, or clothing line be charging 20 percent more?

The researchers don't address these questions specifically, but their commentary is hardly reassuring: "We suspect that even greater divergences are present in other product markets where gender is always known," they write.

There's not much chance that this difference is due to something other than the gender of the seller. On eBay, women have slightly better feedback scores than men do, overall. Women tended to set slightly higher start prices than the men did, which, in general, is correlated with a higher final price. On average, the men had been eBay members for 9.8 years, the women for nine. But women sellers "received a smaller number of bids for their products and obtained lower final prices than did equally qualified men selling the same products," write the researchers.

The researchers also did a fairly simple experiment to see if their findings might hold true in a non-eBay setting. They went on Amazon's Mechanical Turk site, and offered 116 people the opportunity to buy a $100 Amazon gift card. About half the people thought they were buying from "Alison;" the other half thought they were buying from "Brad."

"Alison" got $83.84 for her gift card. "Brad," on average, got $87.42.

Women, it's time to raise your prices.