So what exactly IS koha?
We have been in New Zealand since 2005 and we have JUST, in 2017, come to understand the true meaning of koha.
We used to think that koha was a "donation", and indeed this is what a lot of dictionaries will tell you. However, koha is much more than that and is an integral part of Maori culture, so it often doesn't get explained because everyone understands it - unless you are NOT Maori.
Europeans (generally) take "donation" to mean a small amount of money, say a "gold coin" - a term you often hear in New Zealand. However koha is whatever you feel you can afford and/or what "it" was worth to you. For instance, say someone let you use their meeting room to meet with a client and as a result you won a huge contract. The value of using that room could be THOUSANDS of dollars. Or say you need some help with some heavy work in your garden, then later in the season you might want to "gift" some of your fruit and vegetables to the person who helped. This is koha. Maori tradition also states that you NEVER turn down koha as the person giving it to you has put their gratitude into it. You can give a koha back to them as a thank you, but it should NOT be money as koha is koha, money is money and they should be kept separate.
Maori will think of koha being whatever the other person can afford or value, whereas Europeans will take it as a token donation - and then neither can understand why the other person might get upset.
So if you are European and someone suggests koha, stop and think what it is actually worth to you and how you can gift to the other person.
Gift is a poor choice of word but it's better than donation.