Hello, actually it depends on how many different live streams will be broadcasted?
If your stream count over 100 , then your server needs to have a good hardware .
If you only broadcast your webcam then no need to have intel e5 quad etc, vps can handle your request,
cause webcam like a4tech (classical webcam , bitrate is about 200kb to 400kb with the 1.3mp) can be watched over 400 clients on the server that has the upload speed around 100Mbit . It can be evaluated with the basic ratio and proportion.
client_count = your server upload speed / your stream bitrate . For a single live stream , I want to tell you about one of my work ,
with the vps ( very very cheap vps about max 30$ per m and has 100mbit) 450 clients watch .
This page will be help to you .
http://letheasoftware.com/wowza-media-server-load-balance-and-client-count/