There are more ways than one to get your hands on a cheap pair of tickets, and while it's much easier to browse the web looking for options to buy sports tickets at an affordable price, the first thing you should not do is buying during the release of the tickets.
When tickets are first being released, they are sold at their most expensive rate. What you want to do, is wait a few days to weeks, depending on the quantity of ticket availability, and then look for alternative sites, such as SeatGeek or StubHub, to find the remaining tickets priced below its initial price. Visit here to find more answers at their event page.