Just done a quick google, and found
L260 Queen arabesque, and the
Candy striped pleco, and a
royal pleco
I've seen Royals in quite a few shops, then can reach 13" (according to planet cat), and are 'relatively' reasonable on price, so that seems likely, as it 2.5" already.
The candy striped i've never heard of, the queen i've heard but never seen, but both of these can reach up to 3" or thereabouts, making the one in your shop nearly full grown if it is one of these 2, plus the queen, and probably the candy will carry higher price tags that a lot of fish (not as high as a zebra tho)