Replacing one, the drain field, that is, if allowed, is very expensive in most states due to new environmental laws passed down by federal government.

I helped write the ASTM E2018 standard for property Condition Assessments which first came out in 1999, and my company also provides a full range of environmental consulting services (Phase I, asbestos, mold, lead PCBs and so forth).

You can find them on my YouTube channel and podcast in my profile page or website.Once you have an idea of what you want to do you need to then check with the city or county to determine what is required for all approvals and the time frame to receive approvals.Ask if you have to install curb, gutter, sidewalks, street signs, street lighting or any other special requirements.Are there any specific street design requirements, DOT requirements, permits or traffic studies.DWQ, Army Corp or any other environmental requirements or permits.General permit fees, proffers, water/sewer tap fees and the process of setting taps and connecting.

Is there a mold, asbestos, environmental problem?

From contacts at other firms, to contractors, title companies, property managers, and legal or environmental teams that might work with sellers, staying in touch can prove beneficial.3.

What if the guests at their place figure out the "Environmental issue with their house"?

We have a mobile home park under contract in North Carolina and are seeking referrals to an environmental attorney who can help us assess the risk associated with acquiring a park with a contaminated water well. 

I would guess you would have to put a little money up in escrow that was refundable, then you could go through your everything you need to do but i don't know where you are going to get the money for everything else like plans engineering pre app with city phase 1 environmental.

A lender will require a appraisal, environmental phase 1, and a professional property inspection.

I am not familiar with the price of the relocation, but I have experience relocating them as an environmental scientist for a consulting firm.