Best option IMO is to do the following: 1) Sign up for SEOmoz Pro membership. 2) Use SEOmoz juicy link finder and linkscape to mix and build a list of competitor's top backlinks and new ones (with juicy link finder). 3) Personally contact each site offering cold hard cash based on the value of the link. We use about 5 other tools besides the couple mentioned above, but the average link building campaign will run about $4k minimum per month. This is because each link will cost from $60-$125 each and it takes wuite a bit of time to go through this process. Deeper contextual links on aged pages is the only way to go. I'd stack 10 of our contextual links against 100+ directory links any day and I'm sure the contextual links would prevail.
I'm a big fan of the free one-way link building service found at LinkBuildingSolutions.com The service will build links not only to your home page, but deep link a portion of them to other pages in your site. You can vary the anchor text as well as whether or not the link shows as a Directory style link or a contextual link. It's not the be-all end-all of link building, but it gets the cart going and is automated once it's set up.
If you're interested in building backlinks through blog commenting then i would like to recommend you this service.