To the OP: Without knowing where you live (at least which country), it's difficult to give good advice.
The way knitting needles are sized varies. There are three systems currently in use: the metric system, the United States system, and the UK system. Simply saying "I'm looking for a yarn with __ stitches to the inch/cm on __ needles" may not be sufficiently specific unless you use the metric measurement for needles. Size 4 needles, for example, are fairly small in the American system, and fairly large in the British system, but 4.0mm needles are a nice medium (US #6).
As you've seen, systems for referring to the size of yarn also vary. This page, courtesy of the Craft Yarn Council of America, gives some guidance as to stitches per inch/cm of fine to extra-chunky yarns on various sizes of needles (or crochet hooks) for metric and American needles/hooks, but it ignores the existence of the British numbering system. :sad:
However, in combination with the Ravelry chart I linked to previously, the CYCA standards should help you rephrase your "quest."
Please let us know more specifics on what you're searching for....