As the page says, every donation to development of Precious is highly appreciated and it doesn’t matter how big or small the donation is.
Yes, 1$ is enough
I was looking at the download stats of Precious the other day, and thought that «If I’ve gotten 1$ for each download, I’ve could have paid my bills for several months».
And if it was $1 pr. download every month, I could start to give some money back to WordPress and other developers.
So, yes, $1 is enough if you’d like to donate to the project, no matter what donation option you choose.