Yah the big difference in cost between those fans is going to be features. The Riing leds are a digital system being each led is controlled independently. From what I have read the Enermax T.B RGB are a single color fan and run of a standard 12v,g,r,b system and are not software controlled by default.
Have not really looked around at other fans as the Riing system does what I want it to do and achieves what I was aiming for in my build.