Considering it's like 20 simple requests per second, you can do it on a couple of tiny virtual servers (for geo and redundancy), totaling less than $10 per month.
Yes check this out. What you'll have to do is build the aws sdk into a single javascript file that runs as a Web Worker. These are distributed to over a 100 servers worldwide. Then you would want to invoke the Lambda function from the worker, link below. You could potentially distribute this further by invoking a Lambda function geographically close to that specific worker. But this setup will be very fast already.
https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/Lamb...
If anyone is up for swapping ideas, I made a GitHub repo:
$20 for 55 'servers' spread worldwide isn't bad, with no maintenance overhead.