Generally the scalpers over buy and will start to panic and unload tickets at very good prices the closer the show gets.
It all comes down to whether or not there's enough demand to fill the venue.
If there's plenty of demand, StubHub prices will remain much higher than face value. They absolutely do not ever become available at good prices.
On the other hand, if the venue is larger than demand, then yes -- you can easily score half-price tickets a few days leading up to the show.
But good luck trying to figure out which one will be the outcome. If you delay purchasing, prices are just as likely to keep going up as they are to go down.