Unless you're reading this from the accounts section of Nintendo, we may never know. But experts in the field can estimate, and they estimate that the 3DS costs Nintendo $101 to manufacture.
If that's correct - and even if it's not, it's likely to be damn close - there's a big gap between the handheld's $101 parts bill and its $249 retail price in the United States.
Which is your cue for INDIGNATION and OUTRAGE, yes? Perhaps, but remember, that's just an estimated cost for the "raw materials" needed to manufacture a 3DS. It's not including research & development costs, shipping costs, advertising costs, the cuts retailers may take, etc.
Nor is it including the fact that Nintendo refuses to sell its hardware at a loss, so there's pure profit to be had in the $148 price gap, too.
How much pure profit? Who knows. But hey, if you don't like it, you could always not buy it!
Why the Nintendo 3DS costs £230 [Eurogamer]