Tipping Man with a Van

I'm trying to arrange "a man with a van" to pick up an arm chair and ottoman from the West Village and deliver it to me in Park Slope. West Village is elevator building. There's one flight of stairs in Park Slope. He's charging me $65 for the move. What is the proper tipping etiquette?

Thanks!

That's a good question! I don't know the correct etiquette either and I'm curious what others might have to say. But when I was in the same situation with a man with a van service recently, I tipped $5 on a $50 delivery - the man seemed perfectly happy and perhaps even a bit surprised that I had tipped at all. 

20% percent tip or $13.00 for average service would be most appreciated, 10% or $6.50 for less than average service, not tip for bad service seems seems fair to me.

My impulse would be to tip between 15 and 20 dollars but I'm told I overtip.

15%-20% just like all other service tips. So $9.75 to $13. If the ottoman follows out the back of the van on the BQE feel free to withhold the tip.