is corn flour different from corn masa? if so, is there somewhere i can get it for a decent price?

Yes they are different; masa is cooked and slaked (soaked in an alkaline solution). Bob's produces both products, masa harina and cornflour. The price on their website is $3.29 for the flour: https://www.bobsredmill.com/shop/flours-and-meals/organic-corn-flour.html

pps masa, by the way, is the Spanish word for dough; corn masa would mean the reconstituted "masa harina" (or can be ground from whole corn), which I suppose would translate as "flour for dough" or something of the sort.

I believe "cornflour" is the British name for cornstarch. Masa Harina is something completely different- it is a fine cornmeal made from corn treated with lime, which gives it a very different flavor. Also not to be confused with cornflower 9Centaurea Cyanea- AKA batchelor's button.

For Christina Tosi’s corn cookies.

I’m not convinced they are but I ordered my Bob’s Red Mill corn flour from Walmart for roughly $3