I believe Cirrus is free to use ~
but you cannot use it for commercial product.
I think you can use Flash Media Enterprise Server 4 for commercial purpose, but I haven't seen pricing yet. (or LiveCycle Collaboration Services)
Adobe Flash Media Enterprise Server 4 http://www.adobe.com/products/flashmediaenterprise/
link added, by author
You can also use influxis.com sitead of FMES4. I've heard they upport the p2p stuff!
Forwarding part of the message from Inluxis support. If something changed, please let me know .-)
WD, Sep 23 09:43 am (PDT):
3) As of now, Flash Media Interactive Server 4 will only allow for RTMFP unicast: http://www.adobe.com/products/flashmediaserver/helpmechoose.html. Flash Media Enterprise Server 4 will offer all of the other variations of RTMFP. Currently we do not have any information or pricing regarding FMES4. We will let you know as soon as we have more info.
If you have any further questions, please feel free to contact us.