It sounded as if you were suggesting that a larger screen size as found on the 240 means a higher price, but I understand what you're saying now - custom screens are way too expensive though larger ones widely used by smartphones are viable options.
My mistake - yes, what I really meant to say is, any odd size screen will increase the cost by a lot. That is why FiiO is planning to use a 3.5 ~ 4.5 inches screen as those are still the common option used by low end Android phone, therefore FiiO doesn't need to custom order them since they are in regular production.