The "Prime" set they reference in the article looks awesome but it's over £300! A motor alone seems to be about £50.For schools maybe this is reasonable, not so much for individuals.

I have several thousand dollars of LEGO bricks (or actually my son does), and I've probably only paid a couple hundred dollars for everything.

There are people all over that don't know the value of LEGO bricks and will sell the incredibly cheap. Check garage sales and Facebook marketplace and you will find deals quick.