Not sure how quick you want to be, but if you can put in a bit more time consider establishing an authority site in a niche, especially if you want to build a sustainable business that frees you from the 9 to 5 rat race.

For an authority site all the so called "link building" will be taken care of by your users because you will be so popular, and you will get so much organic traffic that you wont look at Adwords again.

This is pretty much the way I chose and keep choosing. Notice this thinking aligns with that of Google if you have read the Google webmaster's guidelines! Little more effort and time, but it pays in the long run.

Here is one of the best and free guide I found about this that summed it all up very well:
http://mycps.sitesell.com/

All the best.