One thing I've noticed is that if you find a particular image you like but they want too many credits for it - you can google the photographers username and cha

One thing I've noticed is that if you find a particular image you like but they want too many credits for it - you can google the photographers username and chances are they also have accounts on other istock clones. I did this a while back for a series of images I wanted and ended up saving a good bit because I found the exact same set on an alternative site that were much cheaper.