Maybe make it illegal to attempt to resell a ticket at anything above face value, on pain of, well, pain? (As in personal financial ruin & cleaning the gastro-intestinal ward floors and toilets every weekday evening for a year.)
Offical resellers not allowed to charge more than, in the UK say, Royal Mail postage rates and 50 pence handing & packing per order? And not allowed to resell unless they are the sole official sales outlet for that event?
Just a thought - probably difficult/expensive to define & implement as is the problem with these things, especially to cater for smaller events like community hall concerts etc.