While everyone is focused on how much Microsoft will charge for its Surface tablet, there's another interesting, unanswered pricing question about its tablet: How much will the touch keyboard cost?

The touch keyboard is supposed to be one of the key differentiators between the Surface and the iPad. It won't come for free, though.

Citi analyst Walter Pritchard says in a note, "In our view the keyboard margin (50% on a $60-100 accessory) could help substantially with the economics of the product, putting a $500 price point as mostly likely initial price for ARM-hardware, but making $400 within reach by 2H13."

Pritchard is mostly speculating here, but he did write his note after talking to Microsoft executives.

For comparison, Apple's smart cover, which doesn't have a keyboard in it costs $40 for the polyurethane version, and $70 for the leather version.

See Also: Pritchard's Hands-On Review Of The Touch Keyboard

More From Business Insider

• Check Out The Massive Chinese-Built Ghost Town In The Middle Of Angola
  

• Mitt Romney Gave $1.5 Million To The Mormon Church In 2010... Guess Who He Gave Another $1.5 Million To?*
  

• Bill Gates Explains Why Microsoft Had To Punch Its PC Partners In The Guts