I am looking for software i can buy to manage my Small Business. I am
looking for something which lets your manage everything - ie write
your Business Plan, YOur marketing plan and how to track it and
execute it, your operations documentation , financial calculations and
invoicing, the lot. It's like quicken - CRM software - Business Plan -
Marketing Plan - Sales Plan software in one. It must cost less then
$300.

I doubt you can find much for that price. You should look into hosted
CRM vendors such as <a href="http://www.crmondemand.com">CRM on
Demand</a> from Siebel or http://www.salesforce.com.