3d art is a computer intensive hobby. You won't be able to do it on a potato. If you can't afford a $400 dollar computer, 3d art isn't for you. That is just how it is.

Go to ebay - 8 core/16 thread workstations can be had for under $400. You can do a lot with these.

BTW, if you tell us what you are working with today, we can give you an upgrade path.