I can tell from Delhi. If you're lucky, you may get a direct bus from Delhi to Sonprayagnat 9:30pm from ISBT Kashmere Gate. The bus will be ordinary and cost ₹850. After a long journey of 17-20 hrs, it will reach Sonprayag. Take a shared taxi to Gaurikund for ₹40, the starting point of trek and begin your journey. you can get rooms at Kedarnath for ₹500-1000. Mind you, please take a night rest at either Sonprayag or Gaurikund before starting early the next day as not doing so will wreck havoc on your body. And stay is cheap but food is very expensive on the way