In today's NBA do you really have to have a dominate center? Miami, Boston, San Antonio and OKC don't have one. Duncan is still very good, but is not the player he once was and is more of a tall power forward than a center. Dwight Howard is the only center in the league that carries his team, and when he does they're very good - but not a team you feel you can't beat.
The number two and three centers in the league would be Andrew Bynum and Roy Hibbert, both good players but neither are dominate players. As good as Bynum is the Lakers would be just another mid to low level western conference playoff team if they didn't have Kobe Bryant. Hibbert has his moments, but do you really want to dish out $70 million for a guy who gets 11 points , 11 rebounds and 3 blocks per night? You could spent $20 million or less for 8 points and 8 rebounds, so is paying the extra $50 million for an additional 3 points and 3 rebounds worth it? Plus it's easier to find a 15 point - 10 rebound power forward that it is to find a 12 point - 10 rebound center.
Against 90 % of the NBA teams a starting tandem of LaMarcus Aldridge and David Lee or JJ Hickson would be just fine. I'm just wondering if a team is not better off having 2 very good power forwards on the court at the same time than one very good power forward and an above average or good center.
I think going with Aldridge and Hickson ( or Jared Sullinger) with someone like Chis Kamen or Robin Lopez coming off the bench for size against bigger teams would work. The spend your free agent money and other draft picks on the best players available.