Image subject quality is professional, and there are currently more than 6 million images to choose from, images can be purchased individually without the need to buy credits. Interestingly yaymicro have re-introduced a subscription offering after previously dropping it.
High resolution images command a price of $19.5 (single purchase) while the lowest resolution images are $1.95. Our price listed below is for the cost of one image at $5.80 - the nearest larger size to our yardstick 1200x1600 size (5 credit pack). As stated above there are no actual 'credits' but the multiple purchase packs bring the size of the extra-large images down with significant savings from $19.5 to $4 each.
Yaymicro selling points are simplicity and image quality, they certainly seem to deliver on this.
Disappointingly just handfull sales for me in 2014/5, Bumping Yay images way out of the top 10 list to 21. Although Yay have been trying with several restructures of subscription offerings over the past couple of years, they seem to be stuggling to gain market share. (seem to be loseing market share!)
Nov 2016: I'm not seing a lot of activity from the move to "yayimages".
I suggest you upload your images elsewhere.