Most (if not all) of the authors of Lemmings remakes do so in their spare time, for their own enjoyment / their own way of contributing to the community. I don't know about any others, but I wouldn't want to receive donations in regards to NeoLemmix.
However, while the site doesn't cost a huge amount, there are costs involved in hosting it, and donations towards that would indeed be appreciated. I'll PM you about this.