Rugby fans say they are stunned by the money being demanded.
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And now rugby bosses have waded in.
IRFU communications director Stephen McNamara stressed that fans should only buy tickets from official sources.
"When the IRFU becomes aware of tickets being resold above face value, we follow up with the original purchaser, where sufficient information is available to identify them, and request that they desist from the practice, or their ticket will be cancelled," he said.
However, the Irish Independent reporteed that one ticket reseller site, Viagogo, stressed that people who demanded "silly prices" usually did not sell them.
"Viagogo is a marketplace and provides a secure platform for people to buy and sell tickets.
"Sellers are free to advertise tickets at a price of their choosing and, for popular events, prices can be higher because there is a huge demand and limited supply.
"But tickets listed at silly prices rarely sell," it said.
