Everyone is using some of the article syndication networks with thousand of blogs (mostly crappy ones). Where the only content is other articles unique or not that much from other webmasters, often competing with you. It still works, but sometimes it's not enough. So let's say that there is a private network of 40 news sites (with news on general or various topics) that have actual real and quite good content on trending topics updated 5-20 times per day. Which guarantees high indexation rate. It takes limited number of clients, so there are just couple of webmaster's articles among the real trending content. All the sites are 3 to 12 years old, mostly 5-6 years. PR0 to PR5 with sort of a natural dispersion. Which means more PR0s than PR1s, more PR1s than PR2, bunch of PR3, several PR4 and couple PR5. So how much would you pay for your spun article with up to 3 links to be submitted in this network on a schedule you set? And with 100% money back guarantee if you don't get improvement in rankings for whatever reason?
About $50 by considering the content is not unique enough and this kind of network mostly have huge number of OBL
I prefer 5 USD or more per article. This spun article must be 40%+ uniqueness and it requires a lot of effort to create a readable spun article. It must be written with correct grammar and punctuation, readability and of high quality.
Average is 5$ per article on high PR sites, but there are other considerations. Like IP address, Name servers, site owner, site history, indexed backlinks, age, etc. If you have all these bases covered, than $5-10 per article per site. Make the content unique and even offer to backlink there page as a bonus. Good luck.