Fash Media Live streaming

Assuming you are expecting more than a few people to watch there are two main directions to take;

1. Buy the softwate you need - Flash Media Encoder, Flash Media Server, Flash Pro and do some setup/coding. This is best if you are going to be doing a lot of this and want to minimise long term costs (still I wouldn't call this cheap). If your uber techie then you can minimise costs with Red5 but either way your going to need a decent webserver.

2. Use a content network with an off the shelf solution. (search on Flash Hosting in google). This is about the cheapest and most painless way if its not something you need to do a lot of and dont want to learn too much about flash.

good luck