Arowana grow very rapidly. Do your research, know what you are buying and what you'll begetting into. Then buy a small one and raise it properly.
+1, I would never buy a grown fish. At two feet, that arowana could be a lot older than you'd want it to be, reducing the time you'll have to enjoy it. I think you will have more love and appreciation for your fish if you raise it from a baby size, and you will benefit from the learning experience of it all.