What Shinji is saying is true. It doesn't hurt to keep looking... But they keep finding things of Tanjiro, Mitsuri, and himself. There's a teeny bit of Giyuu as well, but not as much as the first three. He may have already gotten something that was designed after Mitsuri already.

"It's true... But if I keep seeing stuff with Tanjiro's motif on it I dunno how much more I can take before I buy them?? I can't really try to hide it either, 'cause he's gonna find it with that keen nose of his!" It's a huge problem!!