"How much is that desk?"
The demonstatives with ~re endings are basically nouns on their own. Or pronouns I suppose. So if the object you are talking about isn't being named then you would use are, kore, sore, or dare (dare is for asking which, since I dont think we have seen it yet). If you are specifying the item after then you would use ~no words, kono, ano, sono and dono.
In english the words this and that work in either case, as a noun or before a noun, but in Japanese those are two different words. ~re must be without a noun, ~no must be with.
Sono and kono are not really interchangeable, they are this and that in english, so the meanings have subtle difference in location of the item your talking about.
Words starting with ko~ words are near the speaker, like how in english you would use this and here (like this item I am holding here). So~ words are by the listener, like that or there in english (that thing you are holding there) and a~ words do not exist in english, we would still just use that, lol...but they are for things not close to either (that thing or place over there).
Hope that helps.
(その/Sono) is used when the object is close to the listener but not the speaker. "What's that?"
(あの/Ano) is used when the object is not close to either the lister nor the speaker. "What's that (over there)?"
(この/Kono) is used when the object is close to the speaker. "What's this?"
Kono is what you use to say "this."
You should be alright in these lessons using either Sono or Ano when you need to say "that" unless it specifically lets you know whether the object is close to the listener or not.
I'm not sure I understand the english sentence !!! I think a desk is a piece of furniture, right ? So, it's about someone who is asking for the price of a desk, right again ? I'm asking because I'm in the middle of the Restaurant lesson, and a restaurant not the expected place for someone to try to buy a desk. Did I miss something here ? Is there any relation to food hidden somewhere ? Sorry if my question is stupid, I just want to make sure.