These might interest you:

https://gumroad.com/discover?query=MoI%20for%20Game%20Assets

https://gumroad.com/paulchadeisson#AnXXy

If you search for MOI3D on gumroad you can even find some freebies and there are many freebies on youtube.

Some people sell quite expensive tutorials and I can't say they aren't value for money because they are very detailed and comprehensive, but I suggest you don't buy them!

Why not buy expensive, detailed tutorials? Well I think once you get the hang of MOI3D, you will be in a position to build complex stuff from the principles learned.

Good luck