I am pretty sure that Silver Spring tickets are still available from the venue at regular price, BUT, strangely, you have to use the link that is directly from the Midnight Oil presal page:  http://bit.ly/2lMQdNO

which is found on the presale page: https://www.midnightoil.com/pre-sale/

Again, I am not going to this show but I was able to almost buy two tickets at $33 plus fees each, listed as "Fan Club Presale."