This is not a glitch. Shop search shows the 30 lowest priced shops that have that item. There's no specific price cutoff, it just shows the lowest 30. Your Darkophim shows up on the first page because there are less than 30 user shops total that sell Darkophim right now.

(If multiple shops have the same price, they are shown in a random order. If more than 30 shops have the same lowest price, it is randomized which ones are shown.)