I haven't heard of this method either, so I will merely speculate. Bear in mind that I am not an attorney, CPA, or certified in anything in these regards.
It sounds like the buyer wants to "apparently purchase" your property at a high price. They will then be able to demonstrate/justify to whomever that they believe the value of the property is at a particular level.
Apparently paying this higher price would also possibly/maybe give them a higher basis in the property, which would possibly/maybe affect taxation in regards to deprecation, profits upon sale, etc.
There could also possibly/maybe be a tax implication for you if this $10k "waiver/gift" would constitute paying them $10k.