The NIM standard requires relatively high precision and low noise which you will not find in ordinary consumer power supplies.
The question is if you really need to meet full spec to run your particular module? Probably not. Especially if you do not need full current (5A on 6V, 2A on 12V) it will make your life easier. What about the 24V rails, are you sure you don't need them?
Perhaps it would be best if you told us more about your module?
If you just need to power the one, would it not be easier to buy a used NIM crate?
It should only be around $100 and I sure wouldn't design you a power supply for that sort of money.
ST