Gears, like most things in life, belong to the category of get-what-you-pay-for type.
However, like others have said, some gears is better than no gears. So what if you're on a budget and can't afford AlpineStar or Dainese? The lesser brands are a lot better than T-shirt and shorts.
Price out some brands and models to make sure that they fit your budget and then go try out for size to make sure they fit your physique.
I personally will not recommend used helmets because simply you don't know what happened to the damn helmet? Was it dropped? Was it hung on the side of the bike while the dude went 100-MPH and have it bouncing against the frame? Maybe some bad chemicals spilled into the liner and destroyed the shock absorbing foam? Those are the kinds of things that you can't tell just from looking at a helmet.