i prefer to buy refurb laptops, they're much cheaper and still do the same job. who cares if the corner may be scuffed or whatever.
subject specific books may or may not be a good idea. it a pretty saturated market with each uni (even on the same course) often specing different books - and there are many places that advertise near/in the unis selling these books.
classified / second hand section is a good idea.
kithcen stuff, not so much. you can go to tesco and buy a new kettle for a fiver, a toaster for the same etc. so there isnt imo much if any money to be made there.