No tax, no shipping charge. The catch: Walmart wants your e-mail and home address

Source: Walmart

FORTUNE -- If you buy a lot of iPhone apps or iTunes music, Apple (AAPL) gift certificates are almost as good as cash.

Indeed, there's a lively trade in iTunes gift cards on eBay (EBAY), where a $100 certificate will fetch anywhere from $82 to $109.99 on a Buy It Now basis.

Now, as The Verge notes in its latest "Good Deal" tip, Walmart (WMT) has entered the market, selling electronically delivered iTunes gift cards for 20% off. There's no sales tax, no delivery charge, no dealing with sketchy eBay sellers.

The catch is that like any online purchase, you can't make it without giving Walmart your name, address, e-mail and payment information (PayPal and major credit cards accepted).

Walmart's privacy policy is pretty straightforward: They'll use your personal information any way they want to short of selling or renting it to third parties. From their "privacy policy" statement:

• Walmart uses your information to provide products and services and to support core business functions. These uses include order or service fulfillment, internal business processes, marketing, authentication, loss and fraud prevention, public safety and legal functions.
• We may combine all the information we collect. We may disclose your information within our corporate family of companies.
• We may disclose your personal information to third parties under the following limited circumstances:
  • with service providers or suppliers that help with our business operations or joint products. [See note.]
  • with your consent.
  • when necessary to protect the safety, property, or other rights of Walmart, customers, or associates, or when otherwise required by law.

Note: Walmart has business relationships with a long list of suppliers, from Baby George clothes to Gold's Gym exercise equipment.

If all that is okay with you, $80 is a bargain. You can get it here.