Contractor offering to carry repair costs

Last year I found a house in the framing stage of construction. Long story short, I decided to buy it for my personal home. During the construction I got to know the builder pretty well.

Yesterday, I mentioned to him that im interested in flipping a few houses. Come to find out he currently flips houses for his RE attorney. I didn't have much time to get into all the details with him, but basically he said he floats the construction costs and gets paid after closing. He is willing to do that or just work for hire.

I was wondering if anyone has any experience with this type of deal... I can see how this could keep costs down because the contractor has skin in the game, but on the flip side if I negotiate a killer deal for the house and sell for a huge profit this may actually cost me more on the back side...

What Do Y'all think?!?

DW