Show up to the gig... and you most likely will meet people and or scalpers with tickets they are interested in selling... the closer it gets to show time, the cheaper the tickets will become. For example, my sister and I bought VR tickets on eBay, and it came to more than $100. Someone we met at the concert showed up at the venue with no ticket and a few minutes before VR hit the stage, bought a ticket from a scalper for $20.
Good luck. Hope everything works out for you!