Inspection found moisture in basement... now what?

[Selena Walsh]

I am buying a duplex off MLS and just had the inspection a few days ago. The property is in decent shape for a 1950s era duplex. Many of the items the inspector pointed out, we had seen during the showing.... except visible moisture/water in the basement. Our showing was prior to a spring thaw and rain over the past several weeks so we did not notice any visible moisture at that time. The sellers have recently put new insulation and vapor barrier in this area of the basement (it would appear to mask the moisture problem?) so the inspector was not able to see exactly where the water is seeping in and if there are any related foundation issues. There were a couple cracks on the exterior of foundation that would need repair.

We've asked the sellers permission to have an "invasive" inspection to have someone remove the insulation and look at the foundation. 

It is very likely that adding new gutters and redoing some landscaping and grading around the house would make a world of difference on the moisture issue and this will not impact our immediate ability to cashflow the property.

My partner and I are newbie investors and only on our second property, so I feel like we have more of a "homeowner" mindset than an investor... How do experienced investors view things like water/moisture in the basement of a property? Is it all a numbers game? Our mindset is that if there is substantial cost to repairing the issue, we are prepared to walk away from the deal if the sellers aren't willing to reduce the price a little to compensate. Are we overreacting?  Any points of advice are welcome!