Apple sells the newest iPad at $499 for a 16GB model, $599 for 32GB and $699 for 64GB. It also retained 2011's iPad 2, which sells for $399 (16GB).

And it looks increasingly likely that the Surface will also have to face a smaller, less-expensive iPad, tagged as the "iPad Mini," which Apple is expected to announce next week and at a price between $250 and $299.

Singh was confident in his estimates, saying that because the BOMs were based on previous teardowns of other tablets, "They should be within a 10%-15% range of the actual BOM."

But he admitted that the process isn't foolproof.

"Guesstimates come into the picture for components that don't really have an existing cost estimate, for example a ~150 PPI [pixel-per-inch] display on an iPad Mini or a magnesium casing for a Microsoft Surface," Singh said in his follow-up email. "Here, part of the guesstimate involves finding out the cost drivers for that particular component based on existing estimates."