I think what you're saying is that K-r is cheaper in SGD, while K-5 is cheaper in USD...
You make it sound like K-5 is cheaper than K-r in US..
So simplistic ar, like that I buy French Fries in SGD in Singapore cheaper than USD in America, means every single item on the MacDonald's menu will be cheaper in SGD in Singapore as compared to the figure for USD in America...?
There are other things in the equation, like I said. Taxes, shipping costs. There is no such thing as Emjay receiving teleported K-5/K-r from America directly without going through customs, and having negligible transportation costs. Additional taxes on the sale price could lead to a widening of gap for price differences, if you haven't realised by now. For example, for a $800 difference, an additional 1% tax would give rise to a $8 difference.
To me, looking simplistically at things can sometimes lead to massive confusion. The issue here is the approach - it attempts to view different country's dollars as on par in context within the country. The truth is not as simple as that. How can you understand what is going on if you choose to find a quick answer to say, complicated issues such as cancer?