This last one is super longshot both in general, as well as in this particular case since the OP didn't file a claim for 4 years which makes it very difficult to convince a judge that you were harmed in any significant way and still decided not to file a claim until years later. 

I dont think that was the OP question.. 

So what's the average that everyone paid, and what would you recommend the OP pay max?

OP said "the seller wants to back out within 24 hours of signing the PSA".

I did 4 deals last year with partners that were all cash.I am also curious about why some folks are trying to convince the OP not to buy all cash. 

Sorry to hear of the issue for the sake of the OP but glad somebody voiced up in contradiction to the folks who do not see this as a sizable risk.  

To the OP, debt is what you make of it.

OP, you are asking a great question. 

this is one of those posts where "can it be done," and "should the OP do it," are totally different questions.and I think @Carlos Ptriawan nailed it. 

See, I can tell you "Don't do it", but you have to take my word for it, or I can teach you the logic and reasoning why not to do it, and with the lesson learned here, you can use the new acquired knowledge and insight to actually pick the right strategy without you having to listen to other people that they themself have not got it figured out yet.The BIGGEST mistake I see EVERYONE make here on BP.So OP, again..Why door-knocking?