If you can stand being hated and can tolerate 50 emails a day asking for money back followed by 50 more written in 'death threat red' then it's a great way to make money.
Think about it, you're making people pay for being ignorant or stupid. Ebay user policy states that anyone under the age of 18 should not be using the service so no minor is going to be exploited as long as the rules are followed. If people don't read auction info correctly then they should be punished so they know better next time, if it costs them 99p - £130 then so be it, it'll help them massively in future when they're doing more important stuff like signing mortage agreements etc.
Personally I wouldn't do it, I haven't the evil in me but at times I have been tempted, and hats off to the guys who have pulled it off, they may be arseholes but they're richer than me and if they're clever enough no one will ever really no who they are in person.