This has actually been running for a few weeks now. Have now bought 2 boxes.
Requires a Gilmours membership which is free if you have a registered business, or $99 once for personal shoppers. Seeing as Costco is $60/year this is a better deal in the long run.
For the most part, Gilmours is pretty mediocre on the deals compared to supermarkets, but they're good for very certain things (like 5KG bags of frozen chips, and random bulk meat deals like this one, eg it's not a rare thing to get boneless pork for like $5-6 per KG, I buy a lot of it for making sausages and tonkatsu).
Pork ribs everywhere else starts around the $12/kg mark.
Each box appears to be three full racks, and depending on how gluttonous you're feeling, half a rack is normally good for 2-3 people.
Where do you normally get the flyer? so we can check deals. Like you mentioned the price in-store is very mediocre. Would like to subscribe special deals and check what is on special.