It's yet another "purchase advice required" thread from NicolasB. (They're not rationed, are they?)
Requirements this time are a little easier to summarise.

Basically there are just two:
1) As good a camera as is feasible.
2) Access to some sort of app which both edits and distributes photographs. The end-user has some experience with Instagram, and likes it, but obviously that currently only runs on iPhone; anything with similar capabilities would probably do, though.
The tricky part is budget. I could possibly spend quite a lot on this, but I'm definitely hoping not to have to. I guess I'm looking for a budget "sweetspot" - the point where, if you spend less than that, you noticeably compromise camera quality, but spending more than that results in much less significant gains. I don't know how much money that is.
I'm definitely open to the possibility of buying something second-hand to keep costs down.
Something where the design philosophy is more "a camera with a built-in smartphone" than "a smartphone with a built-in camera" is, I guess, what we're after.