Sorry I missed the questions to me lately! I'll try to answer all of them:
Jonny,
Not too many secrets to tell, I guess. Because we live on campus, we walk to work. When we do go out, we almost always take buses and very, very rarely indulge in taxis (only when we can't figure out how to get there from Google maps). And because we're married, we don't go out for drinks 3-4 times a week or go on dates all weekend! We both indulge in 1 hobby separately (my husband takes tae kwon do, I do calligraphy lessons every week), and like I said, we only eat out on the weekends. Eating at home we either eat ramen-like noodles or in our school's canteen (about 7-10 RMB per entree). One huge help with our finances is the way we get paid. One of us gets a cash allowance at the end of the month, but one of us gets direct deposit. The cash envelope is our "living budget" so it's easy to see when it gets low to cut back and start slumming it more. But we consider the direct deposit account sacred and almost NEVER touch it except in emergencies. Also, we don't travel much due to our teaching schedules (Sept - Jan, March - July) with really only 3 breaks long enough to go anywhere, and in those times often students will help us arrange cheap or free travel.
Billc,
We EACH teach 8 classes a week (each class is 80 min, so we EACH work 10.5 hours a week). Also, we have separate contracts with the same university. One of us is salaried, meaning we don't get paid any extra for things like English corner, judging contests, etc. It's like someone else said earlier, we basically just do whatever they ask us and it's not overtime. But, one of us gets 60 RMB/hour, so 90 RMB per class period, plus 1 hour of English corner. 90 * 8 = 720 + 60 = 780, the total weekly salary.
I agree that a lot of your budgeting really depends on your activities and how well you can adjust. If you only want to eat Western food you will need more money. If you always want to go out and drink a lot and do a lot of traveling, you will need more money. But it's possible to live on a smaller budget if you are more disciplined and can find enjoyment in smaller, cheaper things.
I also feel that part of your happiness here is based on your employer. If you choose a nice university who values you and genuinely tries to make you comfortable, you will be much happier and won't feel the need to constantly buy things. But if your job sucks, of course you'll want to go out more often and spend more money.