If we assume $30 per pax and you are your partner is going, you can pack around $80 to $100 for two pax. If you are going alone, probably something more than $50 per pax.
If you are going with your friends, best to check if what they are bringing or if they are packing ang bao. It is always polite to ask your host if they need you to bring any food.
Alternatively, there are some who prefer to give gifts instead of angbao. There are some who will just buy a cake or bring a bottle of wine instead of coming empty handed.
My thought is that even though he already got everything he needs, you can still ask him if they "wanted" anything else, then and share with friends and buy. It would be something more lasting since it could be a furniture that last or something more meaningful just pure ang pow. Otherwise, ang pow is still the most practical :)
I would actually prefer to give an IKEA gift card eg $100! And let the couple or family decide what they would want to buy instead then go and buy that item. Eg a toaster, breadmaker, or vaccum cleaner etc. :)
Ang bao I would reserve for CNY or Weddings... At least that is what I would do from experience haha.
Haha why don't you just give based on how much you can afford to give, as well as how close he is to you.
To be honest, I don't really like this "market-rate" values. Everyone has a certain degree of closeness with their friends, everyone earns a different amount, and everyone has different struggles in life. I can't expect a person who is the sole breadwinner of a family of 6 to give the "market rate" and base our friendship off that.
Just give from the heart, I think that should be enough.