I use vpscheap.net for my side projects. They are very good. They have unmetered bandwidth plans that start as low as a couple bucks a month. I use the 10 dolla

I use vpscheap.net for my side projects. They are very good. They have unmetered bandwidth plans that start as low as a couple bucks a month. I use the 10 dollar/month plan, and it's 1gig ram, unmetered on a 50mbit/s link, quad core, 100 GB ssd. You can do quite a lot with that. Only thing I don't like is that I can't get a clean install. They seem to have one Ubuntu image, and it's not really minimal, so I have to do some cleaning when I start a new instance. Other than that, it's pretty great. You could run a cluster of 30 of those for your Heroku budget, and I have no doubt that would be an insane amount of overkill. If you were absolutely sure you were going to get killed with traffic, I would spin up a small one of these as a load balancer and put it in front of two web/app servers and do one more for database. That's still just around 35 bucks a month. And you should be able to get that from donations.