Depends on your philosophy at this early stage! They are not currently for sale in Korea so I can't check. Anyone from Japan know?
don't know whether it still helps today but in japan robots are counted as 대(体) and in my sense 명(名) is strange for human-like androids hence 대
Not a big issue, but the English here should really say "two cameras is not expensive". Without a demonstrative in the sentence (these, those, the) the cameras are not actually the subject, but rather an invisible 'it' which refers to the idea of buying two cameras.
Wouldn't "is" require the cameras to be the object of some action, such as buying, shipping, making, etc., requiring the use of 을/를? Or if you have a topic clause do you mark it with 은/는 and then keep the topic marker even if you drop the rest of the clause? I would think "The two cameras are not expensive" should also be accepted.
[edited to remove snark, with my apologies to Zhish.]
A bit off topic, but the 는 topic particle can be used for both objects and subjects as far as I know.
Zhish is doing some literary knitpicking, but his suggestion is a valid one.
You are right, I should have said topic. I think of topic as a class of subjects. I could be wrong. Can you find me a reference that says that 은/는 can be used for objects? Everything I've looked at says 을/를 mark objects. (You're also right that my response was too snarky, so I've edited it.)
Right now, I only found this example for use of topic particle 는 with objects, from here, to emphasize the exclusiveness of the object.
(standard object identification with 을/를) 한국말을 공부합니다 - I study Korean (exclusive emphasis of object using 은/는) 한국말은 공부합니다 - I study Korean (and not something else)
Unless I find some other more official source, maybe it is not as prevalent as I thought/remembered.
Thanks for the edit of your response to Zhish. I often am tempted to be snarky too, but then I remember Duolingo is not Reddit ;)
1) If there are six different cameras on a store display counter, after looking at their prices you might say to the salesperson, "two cameras are not expensive", meaning two of the six are not expensive, but the other four are more expensive. Each individual camera either is or is not expensive.
2) Or if two partners are splitting the cost for a gift of six identical cameras for six other friends, the first might say "Since I am low on money I'll buy only two and you buy the other four". But the second partner might say, "I am just as low on money as you are. Two cameras is not expensive. However, four cameras IS expensive." Clearly he thinks they should split the cost evenly between them. In that case he says "is" instead of "are" because he is talking about a (singular) group of cameras.
It seems like the Korean sentence is appropriate only for the second situation. If so, then the English translation is not right. But maybe the Korean sentence is ambiguous enough to apply in both situations, in which case the English translation is ok, but really both "are" and "is" should be accepted.