What about trying to use Scot Shields as a starter? I would drop the idea if Lackey is re-signed or if Shields doesn't make a full recovery. However, with a healthy Shields and no Lackey, I think this idea is worth a shot.
Shields has obviously been invaluable to the bullpen when healthy. With our rotation solidified and given his importance to the bullpen, it never really made sense to make this move after the 2003 season. But Shields was a very good starter that year, going deep into games and pitching well on a consistent basis. He kept up a solid strikeout rate and surprisingly, walked nobody.
I'm personally more concerned about the rotation than the bullpen if Lackey doesn't re-sign. Weaver is good, but not an ace (pure flyball pitchers have a ceiling if they don't strikeout everybody), Saunders, Santana, and Kaz are all question marks. And while I loved what Matt Palmer did for the team last year, it would stun me if he was a reliable starter based on his career track-record (although he might settle in nicely to a long relief role).
I actually feel pretty confident with Bulger, Jepsen, Fuentes, and Arredondo (who I really think will bounce-back) and the mix of guys after them forming a solid bullpen. Bulger and Jepsen have shown they can be effective for multiple innings if you need them to be. There are also a lot of other good FA RP's out there that shouldn't command too much of a commitment if we feel the need to sign one (and I'm sure we will sign at least one...Soriano would be awesome. Hopefully we get Oliver back too.)
I also realize that Shields isn't a sure thing at all next year. It could be that his best days are well behind him. Nonetheless, it was obvious that something wasn't physically right last year. If we can't pay Lackey tons of money and don't want to give up the farm for an ace (that we will also be paying a lot for), it strikes me as an interesting in-house option that is low-risk, high reward.