Well, I think you should look at "Warriors For Hire" . You can buy some High PR backlinks there

Tread carefully there. There is a fine line between spamming and doing it right when those methods.

Just because your competitor is ranking now with them doesn't mean he won't fall off the map tomorrow.

If you're #4 already, I would spend my time building just a handful of super-high quality links instead of going on a low-quality link spree. Just 1 good guest post link, for example, will outdo hundreds of his sub-par links. Your link will also stand the test of time, his will not.

Depends on the age of your site, the older it is the more automated tools you can use. If its a new site then just keep adding high pr manual RELEVANT links.

5 links that are on pages with PageRank per day should be OK, but I suggest you mix up your anchor text variations.

Go for quality in terms of PR, relevance and a low number of other outbound links on the page. One decent PR2 link is worth thousands of crappy little PR 0s

The number of links you may be building per day doesn't actually matter.

What you should consider in the first place is the quality of links and the ways you acquire them. Say, if you blast your site with hundreds of spammy forum and blog comments, then yes, your site can get under Google's penalty.

Also, your link velocity should be consistent - your links should appear in a natural way. Would it be natural if you get hundreds of links in one day and then 0 the next? I believe it's not.

Be consistent. Get 5-10 links per day. Over time, you can increase the number if want to, but be consistent, and consider the quality of your links and the ways you get them.

The more the merrier, but the links have to be real.

You can make hundreds of blog comments, web2.0, social bookmarks per day, but are they "real"? Nope.

Instead try to get the golden nuggets of links = editorial links (placed by other webmasters). If you can get a handful per day, you are already rolling towards great rankings.

Quality over quantity anytime.

Google frowns on mass backlinking and if you suspect the site owner who sits at the top spot for your keyword engaged in spamming, then why not report him? That will make way for other site owners who didn't break the rules. No fair of Google to say they want legitimate backlinking but then reward others who break the rules with top spot on Google.