Pics and ?s about leaking steering box

[bodyart27]

So I just noticed that my steering box is leaking. The resevoir is still just about full so I'm not leaking a ton, but I'd like to know what makes sense at this point.

Rebuild kit ($30+)? And is it worth the time vs. a "rebuilt" steering box at $250-$300. My steering is still relatively good, so I don't think the box is really worn out (185K miles). Does a rebuilt box give me a lot more life expectancy? What else should I replace at this time - the fill and return lines from the power steering pump?

Here is the leak from the top