This is why it pays to get to know people that are working in specific areas who have in-depth knowledge of the circumstances in those areas.

The cost of a cleanup will of course depend on the extent of the contamination (depth and width), the kind of contamination and if it has impacted the groundwater. 

If one can develop in depth knowledge of as specific sub market and zero in on the specific asset class I want (SFR's, small multi families, Apartment Buildings, Retail Shopping centers, Office Buildings ect) than it is much more possible to determine what is and is not an attractive entry price, than determining attractive entry prices in public markets.

Remember, the higher the f number (aperture setting) the more depth of field you create. 

The only people making money wholesaling are the guys selling you all of that education.To be successful connecting buyers and sellers you need to haveAn in depth knowledge of the market.Marketing skills.Sales skills.Negotiation skills.Accurately estimate rehab costs.Understand how to much time it would cost to run a renovation on the properties you are presenting.My advice get a real estate license.

I dont know know the rules regarding depth of pour out there.

@Andrew Carlson@Andrew CarlsonThank you for the in-depth description of the kinds of materials I should be expecting from non-modern houses!

Just like gamblers about their big win and not their loses.  

Then you can read a more in-depth book like The Book On Rental Property Investing by Brandon Turneror The Unofficial Guide to Real Estate Investing by Spencer Strauss.2.

I believe @Marc Winter gave a very good in depth response.