Exactly. And unlisted in the Ultramarines Force Org in either codex are the Land Raiders of the first company (it has LR variants assigned to it which are not part of the chapter's motor pool) as well as the Rhino/Razorback transports which, unless I'm mistaken, are assigned on a permanent basis to about every squad in the chapter. Which means they should have something like ~80-90 Rhinos/Razorbacks (1 per squad, perhaps less in the 1st company and none in the 10th).
I think it'd make sense for most squads to have access to drop pods, too, so combined with the Dreadnoughts and support machinery like Thunderfire Cannons, etc. you're looking at around ~90-100 Drop Pods...
I realize I'm being nit-picky, but this is an insane, over-the-top purchase we're talking about...they could at least endeavour to make it more accurate, yeah? Or, as Arkhan said, have the motor pool be a separate purchase or something.