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.