A container can be had for around $1500 to $2000, and after the studio is finished, you can take it with you anywhere to move to from then on. It's a little cramped, but still highly usable.
This video gives you a good idea about the various stages of construction. You can also find out more details on building your own studio from my Studio Builders Handbook.
You can read excerpts from The Studio Builder's Handbook and my other books on the excerpt section of bobbyowsinski.com.