The service that you're describing is usually called dedicated internet access or DIA. It is a distinct service from residential ISPs, and a more costly one for good reasons. Residential and business ISPs operate a shared resource on which they must impose limits to avoid impacts on other customers. This is as true of PON as other last-mile technologies.
Total ballpark, because it depends plenty on your market, proximity to carrier resources, etc, gigabit symmetric DIA tends to be in the neighborhood of $1000-2000 per month. A lot of the variance comes from the fact that it will be delivered by conventional fiber, not PON, in order to avoid resource contention. So trenching is usually involved in the installation, but the price of that is usually amortized into your 3-year contract.
Total ballpark, because it depends plenty on your market, proximity to carrier resources, etc, gigabit symmetric DIA tends to be in the neighborhood of $1000-2000 per month. A lot of the variance comes from the fact that it will be delivered by conventional fiber, not PON, in order to avoid resource contention. So trenching is usually involved in the installation, but the price of that is usually amortized into your 3-year contract.