Since it is a spectrum, every child is different. I would say some commonalities would be in terms of sensory toys. It i always good to purchase items that will help with sensory or fine motor skills, depending on the age of the child. A compression vest, Weighted balls (like medicine balls), a heavy blanket, a spinning gears toy (my son loves that). If you go to amazon.com and type in autism toys or occupational therapy toys you can get all sorts of ideas.

Sensory toys are great. We also have installed an indoor swing we purchased from one step ahead magazine and a small trampoline is great too.

thats also a great idea. you can go to apple.com and they have the refurbished items for less than brand new.. but they come with warranty and everything.

An iPad if you can afford it.