Sizing guides ands installation requirements -
http://docs.splunk.com/Documentation/Splunk/6.1.4/Installation/Systemrequirements http://docs.splunk.com/Documentation/Splunk/6.1.4/Installation/CapacityplanningforalargerSplunkdeplo...
Depending on data sources, but for 500mb/day POC, you can get away with minimal requirements. A 4vcore/4GB ram VM would probably be sufficient. Disk I/o is a contention point depending on what the use case is for your POC.