We have six grandkids, ages 3yrs old to 10. And right now, they are all riding.
Nancy and I began picking up all of the gear we could get a good deal on at AMA Vintage Days swap meet a few years back. We've picked up like five pairs of boots, 5 chest protectors and a few helmets. Then she watch's for deals at Iron Pony on every trip we make and we always come home with pants, jerseys, goggles and gloves.
The kid's also love getting new gear at Christmas and Birthdays.
The problem is that they only get one riding season in their gear and then outgrow it. There's always plenty of hand-me-downs now, but we keep having to get new gear for the two oldest. (boy and girl).
Buying gear seems to never end now. I've even got gear shelves in my garage and basement and they're full.