Sim, é possível comprar ingressos no local. Como o site oficial do Taj Mahal mostra pontos de venda de onde você pode comprar ingressos.
Ticket Outlets (Buying a Taj Mahal Ticket From Entry Gate Ticket Counter)
Taj Mahal Western Gate :- Tickets are available on Western Gate near Saheli Burj. (Timing-from Sunrise to Sunset).
Taj Mahal Eastern Gate :- Tickets are available at Shilpgram (about 750 meters from Eastern Gate of Taj Mahal. (Timing-from Sunrise to Sunset).
Taj Mahal Southern Gate :- Tickets are available on Southern Gate. (Timing - 8:00 A.M. To 5:00 P.M.)
Tickets may be purchased at all three Taj Mahal entry gates. There are separate queues for Foreign tourists and Domestic tourists and signs will direct you accordingly.