If you guys had (and some of you already do) a decent sum of money, say $xx,xxx - $xxx,xxx to invest in SEO, how would you allocate your budget?
With that type of budget, you get some serious writers AND researchers (not the same) and put some good content on your site. Then you can go after the great links, the pr8s and pr9s.
People here really underestimate the power of the manual review. With great content, you never have to worry about that, and with your competitors writing shitty content (and trying to rip off yours), they do.
Furthermore great original content stays up in the rankings for years with little or no maintenance. Sure everyonce in awhile somebody does an Xrumer blast in your niche and ranks above you in google...temporarily.
On the other hand, great original content is REALLY hard to get out of hired writers. As in really, really hard. It's much easier just order a bunch of links. So I can understand why most people are forced into buying links to try to make a living in this business.
You could probably get into any niche with that kind of budget (higher end).