We don't have synonyms for op-shop yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are op shop and pop-shop.
(n) :
Alternative form of op shop. [(Australia, New Zealand) A shop, usually operated by a charity, to which new or used goods are donated, for sale at a low price.]
(n) :
Alternative form of op shop. [(Australia, New Zealand) A shop, usually operated by a charity, to which new or used goods are donated, for sale at a low price.]