It's best to contact them by email and ask. I've never been able to find anything from the website.
I knew I had the details somewhere so I searched through all my email and finally found it!
It turns out I actually bought them from B & C computervision
, back in January 2014. They cost US$ 4 each plus postage at US$ 15 (I ordered 5 connectors) for a total of US$ 35. They were the ones with right-angles (the connection pins for soldering to the PCB) -I needed ones with straight pins, but it's just a matter of bending them with pliers before soldering to the PCB).
If I'm not completely mistaken I confused having bought them from Best electronics as they also had them, but at a far higher cost, but don't quote me on that . In any case that's the info I have and hopefully they'll still have some of those connectors left. As far as I remember they're custom made for Atari and not a standard connector you can buy from just anywhere (the same thing goes for the PLCC socket for the STe/Mega STe CPU by the way, which I also had to order from them (or was it Best electronics?) just in case someone reading is looking for them.
Please tell us how it goes.UPDATE
: yup, found it on their pricelist
(hopefully up to date) where it says:PRS017 PCB ST 40PIN CARTRIDGE 4.00