Does anyone have a sense of what materials + labor would cost here?

Another way to look at it is that material costs are similar everywhere. 

I do however feel this is perfect for flipping, and paying for the repairs/materials.

I have discussed this with my contractor and he says that to go over it with vinyl is the best thing (the sellers have just painted it but it is crumbling in several areas) and that he has to wear a full respirator setup like he would for lead based paint abatement or other hazardous materials but just screwing into it doesn’t disturb it so much that it is too much of a problem.

That being said, it might cost you a little more than subbing each trade out but you're likely to make up for that cost on the sale and the time you save by working within established relationships.If there are any major issues with the project you're looking to take on you'll want to take pictures if you can so you can send them in advance so any contractors can bring the necessary tools to assess the scope of work.Take a quick look at the materials you're going to need for the site either on Home Depot or Lowes or something similar so that you know roughly what the cost of materials is going to be.

Ron's material is good but I'm not sure how much their "one on one" is these days.

-I believe that I will need to self-manage the property through something like Airbnb/vacasa/vrbo in order to meet the “Material Participation” threshold?

You still need to meet material participation requirements.REPS and material participation are annual tests.Keep in mind there are lose limitations even for REPS. 

That means keeping a fairly decent amount of money on hand to pay for materials/subs. 

Pay for materials yourself if they ask for money for supplies.