No home of a kid with special needs is complete without museum putty, duct tape and industrial strength velcro. Run, don't walk, to the hardware store to get yours now. You'll be glad you did. You will need to attach things to walls, tables and trays so that your kid can reach them from his mobility device or manipulate things without knocking them down.
You can put the museum putty on handles of puzzles or on the end of a stick for picking things up (if you have furry pets, it wont last long, so buy lots). You will also need lots of that velcro, tons of batteries, various bits of foam for padding. Neoprene is fairly necessary also, for bracing and keeping hands on the trike or drumsticks. Never throw away any webbing or strapping, you will use it over and over. Maybe I will put some pics of our crazy house up so you can see what I mean.