You should know how everyone in the conversation is paid. Here it is, plainly.
You don’t pay Harry a direct fee.
Harry receives a flat fee from the dealer.
It stays the same whatever price is negotiated.
Because the fee is flat, a higher price doesn’t earn Harry more.
Ask Harry anything about the arrangement, and check condition, paperwork and final terms yourself before you commit.
Tell Harry what you’re looking for. Let’s take it from there.