normally more or less 1500 USD for an average red in China(size 5'' - 8'').
but if you want a top grade red, it can cost you up to 40K USD or more
price of top grade is never reasonable..
edit. when i say average red, i mean those average high grade(not top yet) red.
i dont really know how much red arowanas r but i can tell you that my blue arowana cost me 249.99$ and i would imagine a red would be at least double that.