let's say one room, 10x10.

rebuilt 10x10 as new construction. $150 /sqf base price. you need to multiply by 2 because you really don't save labor for such a small area. Say 30000. And put in another 5-10 k to fix up smoke damage to the rest of the house, inside and outside.

I probably can do it for 5000 plus another 5k for professional services. but you are not me.