MY DCs primary school used them a few years ago (I don't know if they still do, as my DCs have now all moved on).
The catalogues were free - we just had the hassle of making sure they had the school code on, and then getting them distributed parents.
That was all until we got the commission cheque from yellow moon.
You have to keep publicising the arrangement to keep getting a reasonable amount of money from them - when we stopped doing that, the level of orders (& hence income for the PTA) dropped off.
I think we got between £50 - £100 per year (from a primary school), for not that much effort.
