UPDATE from moooooooo try ISTOCKUP25 for 25% off (and maybe other number combinations are possible)
From their email to me.
"For the next 24 hours, get 15% off any iStock credit pack using promo code ISTOCKUP15 on checkout"
I don't often see retailmenot.com has a some perpetual new customer '10%' off and a '5%' of for existing customer codes but you need to be buying 100+ credits for that.
This seems not to be restricted by the amount you purchase.
I was going to comment above about different stock sources and locations and comparing prices etc .. but honestly in some cases the exact image/composition you have in your head is hard enough to find, and the time spent to find it and comparable ones across multiple sites is often a waste of time given the price difference (unless your after a very large format image I guess).
I know some photographers will submit images to multiple sites and the rates can be different, and some submit exclusively (and get a higher price). I use varying stock sources for this reason - istockphoto.com being one, and I appreciated the discount option and thought others would too.
I got an email with a different code for 25% off - ISTOCKUP25.
You might want to try various code values and see if you can get a better deal.
i would try "ISTOCKUP100" then… :O)
![iStockPhoto.com - 25% off When Buying Credits - Valid Today Only [US Time Zone?]](https://files.ozbargain.com.au/n/44/71944.jpg?h=d7afd477)
FYI started using http://www.canstockphoto.com/ much better pricing and source of images.