Unusual need: marketing with a specific picture

Hi there,

I have what I think is quite a unique social media marketing need.
I want to market to people by sending them an image which is customised for them.

I can easily write a bot to automate any task that I can do manually, but at this stage I am not sure the best way to do it manually.

Essentially:

1) I download someone's profile picture,
2) I modify that picture with a program - adding my product in to it,
3) I then have them see the modified picture,
4) If they click on the picture they are taken to a page where they can share it on social media.

I am happy to use any social network - but would love if I could do it on facebook. (Instagram + WhatsApp also good).

Boost Juice in Australia did this recently... I want to know how they did it!

Here are some things I have already learned:

A) Facebook have a think where you can message someone, pay facebook $1, and it won't go in their spam ('other') folder. I don't really want to spend $1 each time though.
B) I could do this pretty easily by using reddit + imgur, on boards where people post pictures of themselves. Just private message the modified image back to 'em.
C) A facebook group called "Wittybunny" seem to be doing it. A friend of mine got a photo in their feed which was their face being morphed into a celebrity. (Essentially same functionality).

Please help!
Any information is greatly appreciated: happy to pay a fee if someone can take me through a plan in depth.

Cheers,
Don