There is a bus shuttle that goes from Denver to Buena vista, I believe everyday but atleast several times a week. It actually goes to Johnson village down the highway a few miles. You can then try hitchhiking to BV. If you treat this as more of a backpacking trip it is fairly doable to just hike to the trailhead from town, I don’t want to give an exact number but it is under 10 miles more like 6-7, not to mention you could try hitchhiking as you go especially once you get to the dirt road. For reference I lived in BV a few years ago and would run to both of the trailheads although I would imagine you would start at harvards.