Nav 4.0 resources

I'm looking for good resource materials on Nav 4.0. Can anyone point me in the correct direction? I know it is going to cost so if possible I would love a bare bones, but good version and if you can afford it here is the top end version of resources. If there is a middle ground that would be spectacular.

It is hard to find the resources because Nav 4.0 IS so far behind. I also don't want to order something only to find out it was a total waste of money.

Thank you for any input you have to offer.