Under a grand for Razors.
I would think for a 6 foot tank he would probably want 3 Razors - especially coming from 400w MHs. I know you have the Razors and like them very much, but they are very different from 400w MHs, especially running 20k Radiums (if that's what he has). The best bet might be getting something that can accurately copy the spectrum graph of the 20k Radium (or whatever he is using) since he can always fall back on that tried and true spectrum (albeit not coming from a MH). Only he can decide what will suit his tank the best and give him the features he wants. It's going to be expensive no matter what way you look at it - and is even more expensive if he gets a LED that doesn't have all the features he wants and has to upgrade, or worse, revert back to MH. MHs are tried and true - they work fantastically you basically can't go wrong with them. LEDs are new - and are also great (even far better in certain applications, such as my own) - but there is a much bigger lineup of products to choose from and they are not all made equally. The Razors are definitely up there compared to other units, but they certainly aren't the top of the line. I love my Radion Pro's, but that doesn't mean that the OP is going to like them - same with the Razors.
The only way he will like the LEDs he picks, is by actually looking at tanks that have the same lights he wants, and playing around with them to see if they have the features he likes. Nobody should be saying "This is the best light for you" or "You need to get this, it's the best" because nobody knows what is best for his tank besides him.
Buying a LED without seeing it in person and using the software is, frankly, stupid. Unless you are buying some cheapo light, you really need to see the light in action, see the coral it is growing, and use the software. Sure, other peoples thoughts and reviews are important (especially when it comes to longevity), but nothing is as important as liking what you get.
