I am on Bronze level and non-exclusive. If I look at the chart here http://www.istockphoto.com/rate_schedule.php
no commission is under $0.30 at my level and I just sold 5 images at $0.20 each: extra small, pay as you go, regular. The same image has been sold before with commission of $0.23, $0.25, $0.29 under the same "extra small, pay as you go, regular".

I am very puzzled here as to why the commission doesn't reflect what the chart says and why the price vary under same purchase conditions... Am I missing something?

Okay, thanks. I thought IS put a date limit when you buy credits, good for a year or something. These must be years-years old credits! From before 2005 (since Bronze level in 2005 commission is $0.25 for the equivalent).............

Good to know, clarifies everything. Thank you.

I recently had an XS, Pay as you go for $0.10. Never seen that before either.

I've been seeing that a lot lately.  Over the last 2 months, my average per download is less than $1!

No, it is not matter of old or new credits.

In this page: http://www.istockphoto.com/sell-stock-photos-exclusivity.php , read this:

"Note: The above examples are based on the gross credit value of $1.52 USD. Royalties above are in USD. Actual royalties are based on net credit value which varies with purchase."

Your royalties depend on how many credits the customer bought.

While that is true, the $.10 royalty is a very old credit from when royalties were simply a dime.