Re: What items does the worker have to buy...
My brain is the equipment in question, I transfer ownership from my PSC back to human me at the end of every contract and back again at the start of the next. I have the paperwork to prove it (or will have very soon, wikis are great).
If you're going down the CE gadget route, I would say a mobile phone is better as they usually are allowed on the guest network of clients, You can use it for official work communications and leave your personal one at home/in back pocket. You don't even have to buy brand new.
Of course you can have a shiny new laptop every contract if you want and this is a good reason to get it approved by the CFO.