The Loot for Less series describes magical items worth less than 2500 g.p. in Pathfinder, and this volume covers magical rods.
There are a total of nine items here, which is significantly less than in the rings volume, although they generally require a much more detailed description of what they do. Even so, that's less pages for the same price.
Since there isn't much of a clear outline of what rods do in d20 - they're more defined by their shape than their function - the ones here are a varied bunch. Some are substitutes for mechanical devices, with the main advantage being that they're more portable. Others are more 'magical', albeit always with low level effects that would take some ingenuity to use, which is no bad thing.
This is probably slightly less value than volume 2, but the items are somewhat more original and unusual, which partly makes up for the smaller number of them.