I maintain a small open source library for managing payments websites that uses this architecture [1]. My Lambda costs have been about $0.04 per transaction.
Also you can provision AWS from the browser using a CloudFormation template and a Launch Stack URL [2].
It lacks some of the features you'd get with a dedicated backend service but it's truly static and costs about $0.004/transaction on AWS Lambda (not including Stripe's take).
I haven't, but even at this size the rendering is quite a bit slower than the calculation. For example, the delay on reload is almost entirely from rendering the shortest path tree.
The geographic rendering APIs tend to be incompatible with the graphing algorithms and data structures. It's better to optimize your data on the server for algorithmic simplicity and convert to a render-friendly format at render time.
Also, immutability is great when you're juggling 1000s of lon/lat arrays.
Also you can provision AWS from the browser using a CloudFormation template and a Launch Stack URL [2].
[1]: https://github.com/christophercliff/flatmarket. [2]: https://github.com/christophercliff/flatmarket#automated-dep...