How much would you pay to level a wood subfloor?

[Byron W.]

I'm in the middle of a bathroom rehab. My contractor ripped up the floor tile and noticed that my subfloor wasn't level and in bad shape, I took a look and agreed. The rehab itself is in a bathroom that's about 60 square feet roughly and is costing me $3500 (our agreed upon price). However, for leveling the floor, he's quoting me $800. After some negotiation, he came down to $600. Bringing me at $4100 total in labor for this rehab. The rehab includes installing a new tub, vanity, floor and shower tile, mirror and light fixture. Am I being ripped off for the floor leveling cost? It seems pretty steep to me but I've never encountered this issue. Any thoughts would be appreciated.