This is going to be, by far, your biggest post-arrival expense and although you can ‘almost’ take or leave a flight reimbursement from your employer (it’s always worth asking, of course) you should definitely negotiate for a housing allowance included in your salary package. The flight is bought once, the rent is ongoing.
Depending on where you wish to live and how (shared flat or by your lonesome) you should budget about USD 700 a month for a Tier 1 city central apartment – and a lot less if outside the city or in Tier 2 cities. When negotiating a rental in China, you will need to fork out three month’s rent and, if you use an agent (which you really should) you need to pay their fee as well. All of that means that you’ll need to part with about USD 2500 the moment you find a suitable place, which in all likelihood will happen within the first 5-6 days of your arrival (everything happens really fast here). Now, do note that no matter how ‘nice’ your new boss is, no-one’s just going to throw allowances your way so you need to learn to negotiate for what you want. It’s not uncommon for the school to pay for your hotel for the few days after you arrive, to offer the service of a staff-member to help you find suitable accommodation and to either offer you subsidised living OR an allowance, paid on top of your salary, to help cover the rent. Housing expenses are certainly the ones you’ll want to have coming back into that piggy bank of yours.