Help me purchase a Boxster

[gameboy]

I am thinking about finally picking up a Boxster (been wanting one for a long time). I would love to pick the brains of experience Boxster owners around here. Please help a newbie.

I want to spend less than 30k and definitely want a 987, preferably 2007 or later.

Looking at local listings, I see following choices;
-2006 S, 50k miles, ~$30k
-2008 Base, 26k miles, ~$33k (seems really steep, probably has some room for haggle)
-2005 S, 35k miles, $28k

What would you do? Is buying an S really important with 987's since they have about as much HP as 986 S? What about tiptronic? Should I stay away from that (though my wife would prefer that option)?

Thanks for any help.