Otherwise, yes you have to either excavate and repair and replace or run a pipe burst through the line, which is usually as expensive as excavating. 

A roof on the 600K property will cost more than on the 300K property, but you have more roofs to repair on the multiple 300K properties.

Deduct NEW property taxes after you buyDeduct home insurance costsDeduct maintenance percentage, typically 10%Deduct vacancy+tenant nonperformance percentage(we recommend 5% for Class A, 10% Class B, 20% Class C, good luck with Class D)Deduct whatever dollar/percentage of cashflow you wantNow, what you have left over is the amount for debt service.Enter it into a mortgage calculator, with current interest rate for an investment property, to determine your maximum mortgage amount.Divide the mortgage amount by either 75% or 80%, depending on the required down payment percentage - this is your tentative price to offer.If the property needs repairs, you'll want to deduct 110%-120% of the estimated repairs from this amount.Be sure to also research the ARV and make sure it's 10-20% higher than your tentative purchase price.As long as the ARV checks out, this is the purchase price to offer.It is probably significantly below the asking price.

I learned this the hard way personally and had to get mine repaired.

@Reeves Bennett Focus on quality over quantity. 

A seller could also refuse to pay any concessions for buyers closing costs, appraisal required repairs, etc. but it would be to their own detriment.

Are their listings detailed with good-quality photos?

I’ve had to rent in the offseason before and have gotten quality applicants but it does take longer. 

So there will be the cost of the inspections (not cheap) and the cost of the repairs.  

In my experience, Section 8 tenants are low-quality.