Ive went threw twice, set up a business plan for the 3 rentals, had a professional heating and plumbing company go threw and give me an estimate.

Grab 3 estimates from local contractors for repairs, lets say ~25k.70% ARV - repairs puts the cost to the flipper at 45k.  

Scott The Book on Flipping Houses, The Book on Estimating ReHab Costs http://www.biggerpockets.com/flippingbookTo find out about an area go to IREM.org search for ARM certified property managers.

Our 2ndary offer is, as you suggested, a purchase contract with a contingency on the moocher being removed AND the rehab estimates being no greater than our worse case projections, since we can't get inside it.

I would just recommend using the GC and get several estimates unless this particular GC you know. 

I've been pleasantly surprised by the passion and diligence of so many using this tremendous resource.I've bought the book on estimating, and have started it, but obviously vis a vie this question haven't completed it yet.

We have built both companies on intergity and that's one principal we stand firm on, we have licensed contractors to give accurate estimate cost for repair and an offer an home inspection to give the buyers the truth about the home that they are interested in.

I wouldn't let that get in the way of a good deal, just get an estimate and point tucking (filling with concrete) might do.

Scott The Book on Flipping Houses, The Book on Estimating ReHab Costs http://www.biggerpockets.com/flippingbookCouple good reads  9 Reasons You Couldn't Find A Buyer For Your Wholesale Deal Don't Start Wholesaling Until You Read This: Wholesale Advice from a Fix and Flipper How to Start Wholesaling: Getting Past The Education and Into the FieldDownload BP’s newest book here some good due diligence in Chapter 10.

I’ve gone out and visited two properties and done rehab estimates using what I learned in J.