The first two articles are by somebody named Liz Pulliam Weston. She lists exceptions for some of them. For example, it might be OK to buy a used mattress if it mostly sat unused in a guest room. See the articles for exceptions.
Buy new:
Laptops
Car seats
Plasma and high-definition TVs
DVD players
Vacuum cleaners
Digital cameras and video cameras
Shoes
Mattresses
Wet suits
Helmets
Buy used:
Books
DVDs and CDs
Little kids’ toys
Jewelry
Sports equipment
Timeshares
Vehicles
Software and console games
Office furniture
Hand tools
The next two articles are off a site called The Street. No exceptions were given, although I can think of some. I mean, there’s boats and there’s boats. I could probably justify buying a canoe.
5 expensive things not to buy:
Timeshares
Boats
Recreational vehicles
Snowmobiles, jet skis and all-terrain vehicles
Vacation homes
5 everyday things you don’t need:
Bottled beverages
Extra food
Diet products
Vitamins
Expensive cosmetics and toiletries
I can think of other things, especially for the “don’t buy” list. Anything on the lists that you disagree with?