If I have a budget on a house that sells for 150k ARV in MI and I budget 40k but something unforeseen makes it 60k I am left with very little profit whereas with home prices in Cali easily over 400k you easily could have 2-3 major miscalculations and come out on top.

Make sure you have a big contingency for unforeseen repairs.

I have received quotes from other sub-contractors and if I stop using my original contractor I can save about $25,000 or 50% of what he will charge me, not including any "unforeseen cost" if he decides to raise the price a few weeks from now.

If you loose a paper here or there, they have copies.When you're working with agents and brokers... again, they have liability, and will help protect you from faulty contracts because it can also protect them and their reputation.Where you need to be careful is when you go to do a deal on your own, without a broker or a lender to review your contracts and any unforeseen implications.  

I estimated the renovations to cost close to $19k, so to be on the safe side, I sent her $25k to cover any unforeseen expenses that might have popped up.

and was able to refinance almost all of the money out... the rehab went over due to some unforeseen issues (beware, this almost always happens, I have now found out).

There are always unforeseen expenses so if they don't make you excited enough at a glance to dig in deeper then PASS!

I'm thinking 70% rule and the margin is pretty thin with not much there for unforeseen rehab problems.

We don't know what your daily reports say, specifically in regard to unforeseen conditions, but those things should have been addressed on their own.

With a 21K margin, all it takes is a couple of unforeseen issues to wipe out your profit.