Is $8,000 to install cellulose insulation and air seal attic a fair price?

I live in a zone 5 climate in the northeast area. I used a thermal camera and saw significant heat loss along the ceiling where it meets the exterior walls in my son's room. When I went into the attic, I found no insulation in some areas, R-38 pink fiberglass in others, and no baffles. We have to keep the heat at 73F on cold days just to get my son's room to 67F. The attic contains electric wires (from pancake LED lights), piping/duct work, and the AC air handler. I discovered mouse droppings everywhere in the attic, which is a problem we've been dealing with for a year. I won't fix the insulation until the mouse issue is fully resolved. I'm grossed out by the droppings and concerned about hantavirus risk, especially since I have a kid on the way in the fall. My spouse thinks I'm overreacting and we should save money. I'm trying to figure out the best way to fix the insulation issue, considering options like entirely replacing it or just adding more R-38 and baffles. I'm also wondering about the benefits of cellulose vs. fiberglass, whether cellulose truly repels mice, if pancake LED lights need air sealing, and if R-60 insulation could cause my AC to short cycle.