Sadly, Apple seems to have convinced many people that a 200-300% profit margin is normal. :/ 10-15% mark up used to be normal, above that used to be considered extreme.
Obviously, there are R&D costs and advertising costs. In LG's case, the R&D costs are spread over many products. The same display tech in this GPad is also the same place they make all their phones, televisions, and yes, the iPhone and iPad screens.
And seeing how LG probably isn't going to drop half a billion dollars in advertising like Samsung and Apple do, a 60-80 dollar profit on each G-Pad is plenty. Especially if you consider that they can't sell it above 300.