The scary thing I saw is that while it's cool that Lambda is $2/month right now, which is negligible, it's $2/month for 900 users. If it scales linearly (and I

The scary thing I saw is that while it's cool that Lambda is $2/month right now, which is negligible, it's $2/month for 900 users. If it scales linearly (and I don't know that it does, because I don't know exactly how the system works), then that means you're one good blog post somewhere about your extension away from being $200-$2000/month. That said, my gut says there's a good chance that since the author is surprised at the rate of requests, there's almost certainly an optimization opportunity that wouldn't even take much effort.