Lol! fun to watch the moment that my affection # changed from 999 to 1000!
500px is a neat photo site. There are a lot of Amazing photographers' work to view on there. It's fairly clean a site compared to some, where there are tons of groups and contests. I enjoy looking at and uploading images to 500px.
Though, as for selling, I cannot comment since I often don't upload a large enough image, and my camera's megapixels don't allow for large print capabilities either. So, I don't bother to pay for an "Awesome" package and most of my images don't automatically go for sale. Selling isn't my motive when shooting photos. The motive for me is more from a personally fulfilling artistic standpoint only, capturing exciting light and shadow and pattern, and finally for the enjoyment of sharing images I am thrilled I managed to get :-)