i don't see the benefit for the agent. it's dumb.
i realize the rehab price will be higher, thus the commission will be higher - but what type of agreement can you strike up that will be sufficient to enforce? it won't be a listing agreement, because you as the buyer don't own the property, so there's no contract that can be signed that would hold any weight, because buyer doesn't own anything.
what's the keep the buyer from buying the property and telling the agent to get lost - "oh i changed my mind."
unless there's an agreement signed at closing.
OR the two parties know each other very well and trust that the other will do the right thing.