And either could do written bid with broken down for labor and material costs.   

A GC is not responsible for making decisions, what kind of *materials* are you going to finish in?

Take the time to learn from other local investors and the material here.

Any house flippers out there buy their materials in bulk or get materials for a discounted price because of there repeated purchases?

Put a few thousand out of my pocket on materials and did all repairs and work on this house free because I thought I was gonna fix and flip and walk away with a nice profit.

buy all the different written materials from different gurus there will be a lot of information in those.. just use what you like discard the rest or resell the package on E bay 

As of right now my plan is to get 2-3 bids from licensed contractors (which I estimate to be in the 8-10K range with like materials) and then submit that to my insurance company but I'm still not sure what my rights are in a situation like this in my state since they plugged everything into their formulas to calculate price.

Does anyone have anything specific apps they use to estimate rehab material cost? 

Materials, labor, permitting, etc. 

The tenants provided all needed labor, and the required materials were purchased slowly from the discounted rent paid by the tenant.