Gift registries, groups, and partial payments

I recently made an online purchase for a friend's gift registry on amazon.com and was left wondering about the room for innovation in this space. Although I purchased the gift, but I really wanted to contribute money towards a more expensive item in the gift registry because it is something that my friend will really like. However, the item was too expensive for a single purchase. Unfortunately, there do not seems to be a way to partially pay (or contribute) towards the price of a more expensive gift on Amazon's gift registries. The old fashioned way of doing it is by giving cash as a gift. The online registry creator can also select gift cards of different values which people can purchase. Then there are cash registries where people can 'gift' money for a baby's college fund or honey moon fund, which is just another play on the gift idea cards or vice versa.

But can we do better? Can we leverage the idea of groups, crowd sourcing, and partial payments to innovate in gift registries?

What if there was a Groupon-like way to keep track of partial payments towards gifts? For example, the creator of gift registry can set a limit like, 'if 50% of the costs for a gift are paid by my friends, I will purchase the item'. The person purchasing the gift can have the option of purchasing the gift, contributing towards partial payment of a gift, or simply paying cash. The purchaser can limit the use of cash, i.e., use it only towards gifts etc.