I do only on page SEO and then outsource the link building to freelance SEO people. There are lots of affordable SEO people out there in India and other Asian countries.
Link building is very time consuming and its good to outsource it to other people who can build good links and take only a small amount of money. It's all about finding such people.
This way you will be investing a small amount of money and if it all works well then you will be getting much better ROI.
@Makaveli2007 What you say?