this is an interesting debate lol, can see both sides, it may only be £16 for a angle grinder and a bit of frame, but when we build something we want it to be good and competitive so i think you would need to spend a bit more than that.
also remember peeps that we all dont have nice machining equipment at our disposal, or cash readily available to knock something together, for someone still at school £20 is a few weeks pocket money! that he might be saving as hard as he can to buy his robot bits needed for his event, but also we are all tightning our belts in this difficult time

i can understand trying to improve the popularity of tool racing, i will build one just to come to your event (but is that the right way of thinking?)
perhaps i will enjoy it and find it a bit of fun, but i still dont find it appealing enough to want to take it seriously, just as a laff.
i just wonder if all that will happen is that a load will turn up, then chuck them at the back of the garage after to gather dust.
but for me, as i want to fight a full combat event of robochallenges it is a small sacrifice, i will not be putting any effort into it though tbh, just any old bits i find lying around lol.

would it help to wave the fee for under 16's? i dont know.