Yes and no, DM
My son has taken part in some of the (now cancelled) TTs. He isn't riding a 1500k bike, he's riding a 2nd hand Al-framed bike that cost about £300. He was only 17 when he took part in the rides, and £5-15 per ride is a lot for a lad his age. He wasn't the only one; Clifton has a number of young riders, the sport depends on new blood.
I know it has to paid for somehow, but it's still not that cheap for youngsters.