I think... Article submission Blogging Forum Participation Press Release submission and, Directory listing
Unique but quality contents with lots of work with web forums and blogs, the way to build links to your pages.........buying links is a stage but not truly at your start up.
I strongly believe in quality and unique contents to develop at ones website and this a good way with initial start up, social bookmarking and contents boosting would make a sense to your pages and good real traffic would start coming at your targeted pages. what you need else?
contents boosting with social bookmarking is a useful way out for traffic grab, if you are website owner then try to write something daily at your own disposal and get good results, creating controversies online is considered a way to get traffic through social bookmarking but rumors give bad effects to blogs. everything should put down under heavy research work then your personal opinion can vary and can cause a traffic flow on to your pages.
Link building is free. You can do this from forum posting(signatures), blog commenting, link exchanges, and article submission.
Blog commenting for regular link building. Also try hard to get a permanent link on other sites with good reputation. These are very rewarding in terms of links.
Try article marketing. Write unique content and spun them into various different versions which are all unique (Use TheBestSpinner software). Submit all this spun articles to various web2.0 properties, article directories and blogs. Good luck.
Article marketing, presss releases, blogs, signatures and yahoo answers are the methods I use for link building. I am thinking about looking into SEnukeX as well so I don't have to manually do all of the submissions
Best Link Building budget must include Article Submission Forum Posting Directory Submission Social Bookmarking