From experience and working for many years as an affiliate manager and affiliate myself the salary can range a fair bit. The bottom end affiliate administrators and newbies to the job get paid about $1,000 a month with the top end, such as affiliate directors make over $20,000 a month and normally have a nominal commission structure as well.
The average affiliate salary for a manager who has been in the industry for a few years I guess would be $6,000 a month, however it varies a lot and I believe several managers are probably under that amount.