The $40 thumb drive is the price to send it to you while they still allow you to download it for free. They give you a free download or a $40 USB drive for a given period of time.
I was under the impression that the free download was a one-time deal but they've downloaded to me at least twice at no charge while on auto-update.
The $149 is the price when the free updates are used up. I believe many manufacturers are moving to a subscription model and MAPS won't be the only feature. Pretty soon you'll be paying to use your massaging seats or better yet your headlights.