Yeah that PLUS
I think it depends on if you are going through a management company or owner direct. All it took for me to get a free night, thus lowering my rate, was a phone conversation with the owner. I didn't even ask for one. By the end she just decided to give it to me.
You'll find some variance between all the different units. I found the low price I liked, then asked another owner to match it since I liked their townhome better. They were great about it.
I found a place on a listing website and emailed the owner to inquire. They gave us $10 off a night if we booked directly through them (vs through the management company). Management companies can't really negotiate since they are obliged to rent the price that the owners stipulate, but if you work directly with the owners anything is negotiable.