If you are unsure about building your own (or hiring someone to build it) then you might want to take a look at one or two of these with CREE lights in them.
https://www.fish-street.com/key_aqua...ategory_id=118
I am planning to build my own too and if you have the budget, Milad appears to be the right track for making a great light so he might be the right person to do it for you.