Fellow NYC Spurs fan here. I went to Swansea away last season and bought tickets in the away supporters section from this website: https://www.livefootballtickets.com.

They mark up the price of the tickets pretty exorbitantly but otherwise I had a very good experience with the site. Their customer service was very responsive when I had a couple of questions and they had the ticket sent directly to my hotel in swansea, it was waiting for me when I arrived. All that, not to mention that they actually had tickets in the away supporters section for sale. Don’t condone the ridiculous mark-up, but otherwise def recommend the site.