Is $2,300 to properly vent a bathroom exhaust fan a fair price?

I am purchasing a property built in 1977. The bathroom fan currently vents directly into the attic, but a home inspection report showed no mold. I realize it should vent out through the roof or siding, and I'm considering doing it myself out the siding. I'm concerned if 20 feet is too far to exhaust out the siding. I worry about going through the roof because it's only a year old and I don't want to cause leaks. I'm pretty sure I can get all the materials for about $200, and I do need a new fan. My dad thinks it's fine since it hasn't caused mold in 50 years, but I know moisture shouldn't vent into the attic. I'm wondering if $2300 is an insane price for this work, especially since it gets to zero degrees sometimes where I'm at.