Depreciation is the discounting of resale value that happens as something gets used. No depreciation has happened when you buy something new.
If you buy something new, you get to suffer the ill effects of the worst part of the depreciation. Did you know that a new loses about 15-20% of its value the second you drive it off of the lot? That's several thousand dollars. Poof, just like that!
You can slay the depreciation monster by buying quality used items, like vehicles, CDs, books, clothes … just about anything, really. There are only a few exceptions, but if you consider whether the thing you're buying is still just as functional as when it was new, then odds are it's fine to buy it used.
Buying things used means that the original buyer took the depreciation hit, not you! You may still get hit with a little bit more depreciation, but not nearly as much. It's a lot easier to slay a monster that's weak, and that's what you're doing when you buy used.