You have to check it very often to see what tickets are going for. All you can ever see at a specific moment is what sellers are asking... and once a ticket sells, there is no record of what price it was at that time.
That said, I just pretended to list tickets, and StubHub helps you price it accurately. Their recommendations for me saying I had row M, side orchestra seats was:
"Based on our data, tickets like yours sell between $2,050.00 and $6,663.00."
So, sounds like those prices aren't outlandish, people are buying them at those prices.