Hey guys

I have a 1993 525 it and it is leaking from the lines or the regulating valve. I live in Ottawa Canada so all the lines are rusty as hell. I have priced a new regulating valve and it is $550. My question is do these valves usually go. Should I try to replace it and or all the lines. And if I do am I going to have to replace the rest of this system peice by expensive piece. Mileage is 187000km. I do not not really want to get rid of the system but it looks like it is going to be a big expensive headache to fix. Any advice would be helpful. Also if all my fluid drains out will it kill the power steering or is each system seperate.

Thanks, Edward