Without knowing the specifics of your situation, I can tell you that I see sump pumps ALL THE TIME and they are quite common around Seattle! Buyers always ask about them, but they do not interfere with sales most of the time.

The bigger question would be did you get an inspection and what did the inspector say? What is causing the water? Sometimes changing up the landscaping or putting in french drains can help. I would just make very sure that you know the cause of the water and how to improve that situation before it hits the crawl space.