hello! is there a bus from guangzhou to nanning? i think it takes 12 hours so i'm wondering if they have a sleeper bus. i have a lot of time to spare so i want to take in the scenery. i'm also a backpacker so my budget is pretty tight. (--,)

which bus station should i go to and what time does the bus leave? how much is the ticket and should i purchase it beforehand? my friend is in nanning already and i can ask her to book the ticket for me.

thanks in advance. ^^v