That's a great extreme kart, but way beyond the financial abilities of my family or anyone I knew. We always kept our eyes out
for things we could scavenge for free or close to it to build our motorized toys.
We were never able to come up with the money for the awesome brakes like that one has. Everything of ours was used stuff (mostly from the mid 60's) bought from people that had out grown out their stuff, were moving to Maryland or something like that.
We rebuilt/refurbished & fabbed what we needed (with parental help, of course). In 1970 we were 12-13.
My dad owned a small family plumbing, heating, AC business.
John's dad worked in engineering at the NAVY shipyard.
Other friends parents worked at Lockheed/Martin.
So if we needed something, somehow we had help getting the best materials & getting the fabbing done.
We thought everyone's families worked with other families to do stuff like that.
On the other hand, we thought that miracle whip & tomato sandwiches with home made soup was a treat.
But it was because of parental bad times.
So, unbeknownst to us, they were all really sacrificing for us. (As an only child, I was particularly fortunate).
My dad's work truck (& later on the car(s)) had all passed through 1 to 4 other relatives hands before us.
A lot of our food came from the deep saltwater creek in our backyard (where we lived in an above the garage apartment behind another plumbing companies owners home) or the local farms.
For me (if I got to go) going to the grocery store with my mother was a treat to a bus ride across 2 bridges to a shopping center. One time my mother & I walked it & our dog followed. I sat outside the grocery store with the dog, then the bus wouldn't let us on the bus with the dog. So we had to call (on a dime payphone) relatives that had a car to come get us.
So, I guess that being poor (and, as a kid, not knowing it) is relative to what your families can scrounge up.
There was this one rich kid (Jessie) that was pretty cool (his family owned several department stores and his dad was an electronics engineer) & his stuff had a great trickle down effect on many of us.