I was told that for people you are not very close to  - like you've described - 100 to 150 quai was fine.

I gave that (200 as a joint gift from me and another) and that was seen as entirely acceptable.

the location is really important. In guangdong, people seem to give less. If they are just aquaintences 200 is fine. You should always give even numbers though. but NOT 400!!!. 200, 600, and 800, is the best. The closer they are, the more you give. In other places, especially more traditional places, they seem to give more. Also pay attention to what kind of wedding it is. If its a cheaper wedding, less is ok. and for a more luxurious one, give a little more if you can afford it.

Remember , that people record the money at weddings, everything is about being equal and fair, people sort of expect to make the money back they spent on a wedding, and if you get married, theyll give you the same or more back ( althought theres a good chance thats not gonna happen in a foreigners case)

So a good rule of thumb is just try to make it equal or better than they soent to invite you.

Ill give you my wedding hong bao prices for reference anyways.

Just co-workers,aquanitances or I dont know there chinese name - 200

people your friends with, but not particularly important- 888

a good friend, in your closer cirlce- 1888

best friends or family- 6888

but the range is crazy, some people think im crazy to give that, others think im a cheap bastard.

  I think it depends on what kind of social status they already enjoy, so if they're rich as hell you'd better get out your pocket book, but if they're poor as shit you can probably get away with giving them some beer-nuts or a packet of Orios.

I've been to about 8 weddings in the last two years in Nanning, and we (my Chinese wife and I) give 100 per person for friends and the wider family and 200 per head for closer family).

Of course it could just be that my wife is a tight wad, but I've been lead to believe that's normal.

I was instructed (by Chinese friends), that 100 is custom for not so close friends and not so good restaurant, 200 is enough for not so close friends and good place.

Wedding in the good restaurant is about twice more expensive per person then standard dinner, so when usually in that place You spend 80-100 RMB per person... it is reasonable to put about 200.

BTW. always sky is the limit

I attended a wedding last friday. I was unsure what gift to give, I was later informed 500 was enough so thats what I gifted. Not sure if it was more or less to be honest, I gave a quick head count whilst sitting at the table they had well over 400 guest's . Not bad eh. I also attended a wedding in Nanjing two years past the couple took over half a million Rmb/yuan/quai. Must say some good learning curves here.

If you are not quite close,200 RMB is ok.