I had been searching in google and here the performance benchmark . Only the Transcoder Addon benchmark I found . First of all
The scenario is different 1000 source ( assume they are ip cam with the rtsp link )
* How many startup streams can start in the demo machine below . (only transcoding by wowza ,transrating disabled )
** How many source can be handled by wowza ( without transcoding and transrating , I'll stream them via ffmpeg ) ( transcoder machine and the streamer machine is different )
*** Is there any input limit that metered by mbits ? for example ,
" if I make the performance tuning and give wowza 10gb ram , and Gc is very big with the heap size "
Wowza max take 70 Mbit input at the same time etc ?

How can I guess the cost , how many machine needed , is there any function or formula for doing this ?
OR try and mistake , try again ?

Demo Server
Processor: Xeon CPU X5xxx @ 3.xx GHz
Cores/Threads: 24/48
Memory: 96 GB
OS: Windows 7 Enterprise - 64-bit
Java: Java 7 64-bit
GPU/Acceleration: Single NVidia Tesla C2070 with 6GB RAM