Koha is a tradition so rooted in Maori society that Maori don't need to discuss it because they all know what it means. Non-Maori often misunderstand the intent of Koha, so here are some words to help you understand it.
Some people try to find a direct translation of Koha into English, but without the cultural background this is very difficult. Koha's intent is more of a gift to recognise something's value than a donation or contribution. If someone says an event (or similar) is Koha, you pay what you feel it is worth, it is NOT just gold coin.
Perhaps it is better to give some examples...
- You want to run a business meeting to secure a contract and you find a venue that asks for Koha. You use the space and secure a contract that's worth millions of dollars. The VALUE of that space to you was huge, so (say) you give a Koha of $5,000.
- You attend a function where they offer Marae-style (dormitory) accommodation for Koha. To stay in similar "backpacker" accommodation elsewhere is about $25 per night so you give $30.
- You are unemployed and on state benefit. You go somewhere where they ask for Koha for their services. You grow vegetables in your own garden so harvest some potatoes, carrots and onions. The VALUE of your offering is huge to you as this is YOUR food you are parting with.
Maori tradition also states that you NEVER turn down Koha as the person giving it to you has put their gratitude into it.
So if someone suggests Koha, stop and think what "it" is actually worth to you and how you can "gift" to the other person.
What is also generally ingrained in New Zealand culture (not just Maori) is that if you are invited somewhere over a meal time, you are expected to bring something to contribute to a shared meal. This doesn't mean you bring your own sandwiches, or food specifically for YOU, but that you bring (say) a chicken, or some dessert for EVERYONE to share. It doesn't matter WHAT you bring, just that you bring SOMETHING.
Cultural note: When someone says "bring a plate" it doesn't mean they are short of crockery and you'll need to bring your own, it means "bring a plate ... of food".