Aside from the hotels in Bu'erjin, where you'll likely spend at least one night after making the journey north from Urumqi, you'll find limited options inside the Kanas Lake Nature Reserve itself. You can find officially sanctioned accommodations in the Tuvan village about 18 km inside the park. There it's fairly basic and quite authentic—cabins and yurts. Prices range from RMB 30 to RMB 80, depending on the degree of privacy you want. Most visitors have little problem with these accommodations, enjoying the opportunity to meet not only other visitors to the park but also mix it up with the village inhabitants, who, during summer months, are given to throwing bonfire cookouts that can go on into the night, fueled by traditional music, dancing and whatever might be in that bottle being passed around the fire.
Camping is doable, though officially frowned on. This is one of China's most pristine areas, and if you do head off on your own into the backcountry, treat it with the respect it deserves (and don't complain if you get caught, stopped and even fined...we told you so). Also, you'll want to bring provisions and adequate clothing for any freelance adventuring, so prepare before you enter the park.