EGR valve cost at a Mechanic's?

I have a 1990 Honda Accord DX 2.2 Lt 4 cylinder engine.
On and off, the car has been driving fine then all of a sudden (Within a 10-15 mins of driving) the check engine light will come on, then the oil and battery light will go on. The acceleration slows down, I lose all power steering and power braking. Finally the car stalls. At first the mechanic's did not get any codes and finally today, after repairing a power steering line, the engine light came on. The code was present and indicated that there's something funky going on with the EGR valve. (I know what it is and its functions). Probably carbon build up. So we're leaning towards that. My questions to you all out there's how much is the part? How much is the labor (It's on the top of my engine thank god)? And will this correct the stalling? I'm a girl but very handy-like and car educated (relatively speaking), just can't pop off bolts sometimes. So, please give me any rough estimates. I sank way too much cash into the Honda. I just want to keep her alive for my last year of college, then I'll bite the bullet, trade it in for a newer car.

I wouldn't replace it, I'd take it off and clean the passages on it and the intake manifold. I'd also make sure all of the connections (electrical and vacuum) are clean.

What make, mode, yr and engine?