Take care of these quality links while buying……
* Link with different title or anchor text.
* Links from relevant theme or topic pages.
* Links come from different locations on the linking pages.
* Links are placed from pages with a varied PR value
* Links not come from pages that links to bad neighborhood
* Links come from both old trusted as well as new sites (better mix)
* Links will not have paid linking footprints around them Words such as sponsors, advertisement
* Links come from pages with the same language.
* Links are permanent
* All Google Cached Links