Thank you Michael,
I think the bulk part of the traffic needed (if I understood correctly the cost part) would be the initial phase where I would need to 'upload' and flag the existing properties in his master file.
From there, the traffic should be restricted to a few "views" per day, and a few new properties every week which obviously I would like to 'pin' as soon as they are saved.
I've sent you an email re: your products, that would be an excellent solution if they can be 'hooked' to the existing desktop app.
Otherwise, I will have to start digging deep, assuming I find a starting point somehow which will explain what exactly is needed to combine that with a desktop app.