New controls
 

I wanted to know how much I should expect to pay for a new set of controls for a 1994 150 HP Evinrude Ocean Pro, newly rebuilt with old junky controls?

The cables, control box, control box with wires or cables with control box and wires?

One thing I was pleased in modifying the last time I had to go into the control box was to remote mount the key switch.
What this did was to remove at least one aggravation having to go into the control box, at least getting the switch and wires out. I did keep the neutral switch active.
Now if it's an electrical problem, don't even have to think about going into the box.

Just the control box

Some of the OMC stuff from e-bay ranged from 80 to $170 used, without a harness. A couple of years ago new non OMC stuff started at $300.
A new OMC plate for inside the control box ran $90 last year.
There are a few options for the control setup depending on which way you want to go. Me, I'd see if you can find the original used stuff.
SKOOLS, you got another one laying around?