Hello, I'm going to the Great Wall at the end of February.

I've been suggested to go to Simatai and Jinshanling sections. I would like to get from Beijing to JSL, walk from there to SMT and then from there go back to BJ. How can I do this? are there buses that depart from BJ and arrive in JSL, and then other buses that connect SMT to BJ? I know that there are guided tours that organize everything for around 40-50 usd per person, but being four people I would like to know if there is an alternative and cheaper way.

Thanks,
Simona