When we bought the box last year, we didn't buy the head knowing we had a head at home.
We had 2 problems with this. First, my son wanted to play with it right away and couldn't. So if you plan on buying just the parts, bring your head from home.
Second problem, when we did get home, we found that our head had arms that couldn't be removed. So all the arm pieces were useless.
By daughter returned to Disney in May and bought my son another box, including the head. The price in May was around $16, but last year the cost was only $12.
This was a great souvenir, and my 9 year old is still enjoying it.