Lost Pet Rock

I found a "Lost Pet Rock" shirt but they are all sold out.

USB Pet Rock

Pet Rock with a USB cable at ThinkGeek.

A Pet Rock Pothead (and Others)

This novelty gift item includes a genuine pedigree pet rock with a handy instruction booklet, a lead so you can take him for walks and a nest for him to snuggle up to sleep in. We'll even throw in a sachet of ketchup (the rock's favourite food). All you have to do is think of a name.

Christmas Pet Rock, You Rock Pet Rock, Marajuana Pet Rock, Jesus Pet Rock, USB Pet Rock. The set also includes hay, ketchup, a cardboard pet carrier, an instruction booklet and a lead.

Found at The Gift Oasis.

Crochet Pet Rock

A softer pet rock available at Etsy, shop ChimericalCo.

Homemade Pet Rock and Carrying Case

Homemade Pet Rock from Etsy, shop VisCrafts.

Pet Rock in Carrying Case with bed and training manual.. Revisit a fun fad from a past era - 1970s. Own your very own Pedigree PET ROCK chosen with care for you. He/she comes in its very own Bed and carrying case. Complete with Owner's Training Manuel on How to Care For and Train Your Pet. All new, except the "Pet".

Nerdy Pet Rock Charms

Not actual rocks, but clay replicas. Cute with their spectacles.

Found at Etsy, shop MyPetiteTreats.