Depending on your power company it may be several hundred to several thousand.

My buyer is willing to pay a few thousand over but I fear that I will be in a difficult position if they were to back out as I wouldn't have any other buyers that would be willing to purchase this contract.The agreement that I use is attached.

LITERALLY!

My experience 1 investment 200 thousand in self storage in Germany have been receiving average cash-flow of 10% over the 7 year history and that does not include the asset value of my 200 Thousand dollars today estimated to be around 500 thousand 

You could possibly apply more down for your escrow deposit to show your ready to commit to the transaction and not just a few thousand to tie down the deal. 

I have heard a few stories in the news over the years where the bill is in the tens of thousands or worse.

Are they supposed to be waiting on the guy to do something about his shoddy work while their house is literally falling apart?

Even missing one component can cost you tens of thousands of dollars.

But I do know that people often spend thousands on a beach house for the week, and depending on its proximity to the water, will pay even more. 

In the summer, we literally pay landscapers hundreds of thousands of dollars and they get the winters off.