For this point you might consider to add a sort of did you know that you can see on a pictures page where it is used? to a sort of thank you message. Another thing could simply be a list of pictures used a lot (and other similar lists) to motivate people (smaller things without prices just lists of those) 

Mvg, 

Bas

> Date: Sat, 10 Mar 2012 00:56:46 +0100
> From: platonides@gmail.com
> To: wikilovesmonuments@lists.wikimedia.org
> Subject: Re: [Wiki Loves Monuments] The philosophy behind the few rules we had in 2011
>
> On 09/03/12 21:58, Yaroslav M. Blanter wrote:
> > There is one thing which we did not emphasize last year (or at least I
> > have not seen it emphasized): that many of the picture they upload actually
> > very quickly end up in lists and some of them end up in articles. I think
> > many of the uploades do not realize how to look up where the images are
> > used, and it is extremely motivating if you upload an image of a monument
> > in Portugal and it ends up being used on Finnish Wikipedia. I think this
> > year we should pay attention to this (mey be even think for an image used
> > in most articles globally - but here we run a danger of users replacing
> > other images with their image, which is not what we want to stimulate).
> >
> > Cheers
> > Yaroslav
>
> It's also a bit hard to quantify the number of images in articles, as
> many monument lists appear in the NS 0, inflating the usage count.
>
> It would indeed be cool if a few hours after uploading an image, the
> uploader would get an email saying "Thanks for your photo, it now
> appears in Chinese Wikipedia"
>
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