"Wow that laptop is REALLY small!" is what I get mostly.
How much are people willing to pay for a laptop? Because that's essentially what it is - OK, it has some disadvantages compared to normal laptops (tiny screen and keyboard, slower CPU, less RAM), but it also has some advantages (huge battery life, built-in game controls, extreme portability). So in terms of functionality they are different but I'd say roughly equivalent.
What do people pay for laptops? I would say typically between 250 and 500 EUR, but up to 1000 EUR or even 1500 EUR for a high-end one.
Given that the Pandora is not produced by huge companies who can get massive economies of scale for their components, a price of ~300 EUR for a base model, ~450 EUR for a standard model, ~650 EUR for a high-end model is not unreasonable at all.
If you have difficulty to justify the price tag, think "ultra-portable laptop", not "fancy DS".