The fact that you can’t see supplemental results anymore itself but you can see PageRank and backlink sampling suggests these are the ways of seeing the difference and the best course to generate better return for your website is the purchase expired domains and then 301 deep-redirect these to make more of your domain remain out of supplemental.
No matter what link building strategy you do – to not get deep links into your website is ranking suicide and the problem with get deep links is costly (link bait being the best) or most places offering say a review will not deeplink. Thus expired domains are an ideal alternative.
You gotta pick and choose what domains to buy though so you can keep a reserve of cash for an alternative solution. This is extremely important.
There are lots of auction places but starting at Godaddy.com (or your own registrar if they have a domain auction) is best.
Places like pool.com, snapnames.com, deleteddomains.com, expireddomains.com, wehavethem.com, etc. are in the business of making money on expired domains – they tend to cost you more but you get privileges that you don’t get in public auctions. Additionally, most private auction that have expired domains that were previously promoted online – are likely well beyond your budget (tending to start at $1,000 and upwards a million for brand value).
Mike Davidson has one of the best guides for picking up brand name domains - http://www.mikeindustries.com/blog/archive/2005/03/how-to-snatch-an-expiring-domain - but don't use that approach here - it'll cost too much.
The greatest reason your want to start at your local registrar you really need to match-up with low end sellers.
e.g. Godaddy.com is a "low end seller" -- they only want to make a few bucks on top of old customer’s domain renewal fees and don't care about PageRank-- They "MUST SELL" and these tend to be denoted by "BUY NOW"!
These are the one you don't need to bid against others.
Buying domains isn’t without the need to do research so you don’t pick up a dud. While I have lots of specialty tools for this I needed to develop a solution that included mostly “freebie tools” or tools already on most computers for other purposes (these will be pointed out as we go along)
While I hate to say this, “PageRank without relevance is enormously valuable”. Remember that I started this as a way to curb pages going to supplemental results. PageRank doesn’t directly make a difference in ordered ranks but it does make a difference to the number of internal pages linking to rankable pages and that “indirectly makes PageRank invaluable to ranks”.
You mainpage doesn’t need to be PR5 – PR10 your deep pages that have viable ranking terms need to be PR3 or more (PR2 you can get away with it).
So as I develop this guide – don’t think I mean 301 redirects to your homepage… you need them on other important pages.