i couldnt find that spesific top other than a few ppl on furrfinity in 2013 but i found https://picclick.com/My-Little-Pony-Brony-Dj-Pon3-Solo-T-221178164604.html <- this which has a bunch of other dj pon3 sirts/merch, good luck on your search !!!
i hope you find your shirt soon, i dont think theres anywhere that sells it now but ill take a look on a few second hand sites and tell you if i find anything :3, it was also sold in hot topic so theres probably a few collecters wholl be willing so sell it to you!!!
hellooo!!! im gamzee, im 14, ive liked mlp since i was a tiny kid, ive been collecting the toys too but mostly just watching n making art n stuff like that, uhhh yeah!!! not quite sure what else to say :3