Overpay to buy a vacation?

[Eric Y.]

While listening to one of the myriad of podcasts I follow to learn more about real estate one of the guests mentioned a way to help a spouse be on board.  First I want to mention that my wife isn't against doing this but while numbers on a spreadsheet and a bank account are good enough for me I think it would be good for her to see some more tangible good outcomes.  This is just my idea, not hers.

So the guest was talking to a friend who had just bought a place for $80k but had a wife that was grumbling.  So the guest asked his friend if he would have paid $85k.  The friend said yes it would be worth it at that price too.  The guest then told his friend to buy it at $85k and take $5k to go on a vacation with his family.  That turns the "negative" of bringing on another property to a positive that the family looks forward to.  There weren't any details given.  This was a side comment.

I've only done one deal but I can't figure out how one would do this.  Let's use the numbers listed above.  Let's say I negotiate down to $80k which is 70% of assessed value.  Wouldn't my bank know that and finance accordingly at $80k.  So, how do I get that extra $5k into my pocket?  Do I ask for a "credit" from the seller?  That seems like it would go badly.  i.e. "I just bought this from you at $80k but I'd like you to sell it to me at $85k and then you'll give me the $5k back."

Can someone help me to see how to do this?  Are there any negatives besides the obvious higher mortgage payment and less equity.  Let's assume the deal still works even at the higher final price of $85k.

Thank you!