I'm not qualified to answer this since I don't work for Splunk, only Sales can give a definite answer. Here is a pricing calculator that Splunk makes publicly available. They have 3 core products which are Splunk Enterprise, Splunk Lite, and Splunk Cloud. If you wanted to keep costs low and have low index volumes and low amount of users, then Splunk Lite will be the answer.
According to this pricing calculator, a Splunk Lite term license for 2GB ingested daily will cost $1,650 annually with support included.
https://www.splunk.com/en_us/products/pricing/calculator.html#tabs/tab3
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