George, You're comparing their petri plates wit
Post# of 9122
You're comparing their petri plates with their BNP kits. Their agar filled petri plates are sold at different prices, from $0.67 to $4.00 per plate based on the types of agars used. The BNP kit as shown contains 2 petri plates, one with a nutrient agar and a membrane and 1 with a staining agar. They are listed for $10.00 each kit. The order page lists on a quantity of 10 BNP kits for $100.00 The page you were viewing shows 25 BNP kits at $250.00. That's still $10.00 per kit. The product page shows an exploded view of the kit.
On the $17.99 each for Pyrex petri plates, that's not a filled polystyrene disposable petri plate. Other than research teaching hospitals and institutes, no one in the US is using many Pyrex petri plates that have to be cleaned and sterilized after each use.
Any company buying polystyrene disposable petri plates in bulk to fill and sell are probably paying less than $0.10 each for them.
Scott