It's easy to set up your own (free) button server though. Here's how: https://bountify.co/blog/host-your-own-hacker-news-button-se...
I honestly didn't realize how much traction it picked up over the past 6 months.. It was a (pleasant) surprise to login into my GAE console and realize that it was serving, on peak days, over 1M impressions.
Interestingly enough, the "exceeded quota" was not for CPU resources! Instead, it was all egress bandwidth. On busy days, it would reach the free 1GB egress limit sometime between 6-12PM, and hence the error. I've upgraded the app, and it should be good for terabytes a day. ;-)
P.S. I've also pushed an update to enable more aggressive HTTP caching on the assets.