In my experience, the cars that have depreciated much of it's value, the next wave of buyers in the market for these cars don't really pay any premium for a full lexus logbook history. (not even lexus).
Although in saying that, I take all my ones to Lexus as its just easier allround. Pickup and drop my car off at work or where ever I am (+loaner), peace of mind because these guys work on the same cars day in and out and do the job well. (I once took my is250 many years ago to ultratune and the mechanic took all day just to change sparks..didn't get to anything else..)
But it does pay to call the various dealer service centers around your area as prices do vary quite abit.