We don't have a flat number to hand you here, and we're not going to make one up. Cost on a new install depends on door size, whether you're going single or double, insulated steel versus a cheaper uninsulated panel, and what shape the existing track and header are in - a straight swap costs less than a job where the opening itself needs rework.
What we can say is that the income gap between Bonner-West Riverside and the wider service area is real, and it's worth factoring into the decision. At $59,609 median household income, a mid-grade insulated steel door is usually the number that makes sense for most houses here, rather than the premium wood-composite lines that get specified more often on the Missoula side of things. Ask for a written quote before anything's ordered, and ask what's included - haul-away of the old door isn't always bundled in by default.