When it comes to getting invited to lunch or dinner gatherings, things are done very differently here in New Zealand as compared with our "traditions" in the Philippines.
In my home country, if you get invited to share in the celebrations (a birthday, perhaps) in a gimmick venue, you expect that food, drinks and associated fun activity (videoke os hugely popular) is going to be paid for by the inviter.
Not so here in New Zealand. When you are invited, you bring along your share of the banquet (if they say 'bring a plate') or, in the case of meals in a restaurant, each is expected to pay for their own meal. Good thing that had been advised me of fellow Pinoys so when I was invited for a lunch out to celebrate an officemate's birthday, I already knew what to expect.
True enough, after meal and everybody started getting out of their chairs, they made a beeline for the register where each advised what they had and paid accordingly. Nobody in the table informed me about it; it's one of those things where they assume you know it already (like the BYOB in restaurants - Bring Your Own Bottle of wine); it's really a good thing I knew beforehand... and knowing is half the battle (GI Joe!)
I guess as Filipinos, it is our strong sense of hospitality that prompts us to foot the bill when we invite people to share a meal with us. The New Zealand way is, or course, more practical (especially for the host!) especially in this time of economic crisis.
Also, when they buy gifts for the celebrant, they would collect funds from the team, purchase items that the celebrant likes (or match the theme of the gathering, such as a person going away for a tramping expedition), and put it all in one box. The celebrant for said lunch, for example, received a number of fun stuff including the latest issue of her favorite magazine, some cosmetics, and her favorite canned food. Whereas in our country, we also pool our resources but would pick out one major gift purchase. Either way, I'm sure the host is equally delighted!
Hope this information is helpful to you in case you visit this part of the world and get invited to a lunch party!