Either way that VPS will cost 10-20$ depending on CPU form a good provider. You can't get that cheap with a bunch of AWS services for that number of requests.
Also, if they were using an hyped tech stack (nodejs or wtv) they wouldn't be able to handle the request spikes like they do. 0.46 requests per second means nothing because I'm sure they've hours of full inactivity and others serving 10 requests / second that would totally obliterate 2GB of ram if done on nodejs and a Mysql DB.