
UltimaGabe |

Simply emulating a particular spell won't really work, because no spell does exactly what you need (there's lots of spells that do what you need, but all of them are either too broad or too powerful for such a simple purpose). As far as meeting spell prerequisites, something like Discern Location would fit the bill (as you're determining the location of one particular magnet), but that doesn't do much to help you figure out the price or availability, because an item that finds one particular magnet is hardly worth the same as something that can locate anything, anywhere.
Such an item should be relatively inexpensive, but still out of the reach of commoners. I'd look at the price of a magic item that can cast Know Direction at will (1800 gp by 3.5's standards, not too familiar with custom item creation in Pathfinder). This item is not quite as good as that, because unless you're using this particular magnet as your guide for anything and everything, then it can throw you off if you're moving over great distances. So personally, I'd say something along the lines of 1,000 gp, unless for some reason you think it should be more difficult to obtain than that.