I purchased event tickets to resell in 2016. Most sales were done in 2016, but some of the tickets did not sell until 2017. How should I report the sales/expenses?

The tickets were bought in 2016, but they were not sold until 2017 which is when I was paid for the sale as well. How should the expense of the tickets be reported on my return? Should the tickets be inventory? I just want to make sure I account for the money I spent on the tickets as it adds up to almost $30,000. Any help is appreciated?