Pose usually means setting Michael or Victoria in a specific manner, say reclining in a chair or in the middle of a jump, saving the settings and placing them into the file for someone else to inject into the model itself to save time and headaches.  They can come in full body poses, split between the top half and lower half of the body, specific poses for hands (say holding a gun or the end of a sword) as well as facial expressions.

Characters...this depends.  There are some that are entirely new models made from another application, yes.  If you see something for V4 or M4 for example those sets are made from dialing the morph sets that have been purchased for Victoria or Michael into a character that looks different but made from the same base model.  I know of several vendors that use the morph sets (base, ++, Enhanced for example) as well as an outside modeling application to create unique character looks for the base model used.

Clothing sets can be expensive, yes.  However the alternative is to learn how to model them yourself, figure out how to UV map them, texture them, rig them so that they fit and bend properly and so forth.  Hence the price.  Most of the vendors do every step themselves, and it is a time consuming task to do such.  I have paid onto 25 bucks for an excellent set of either clothing or props (buildings and such) and trust me-it's well woth the investment.  Usually I stick to a few vendors that I know are on the higher end of the spectrum, but I've found more than few unexpected jewels just by wandering on another artists' site and seeing what they've used.

The same can be said for light sets.  For either program lighting is extremely important-it makes or breaks your piece.  Consider it an investment in your artwork like you'd do with paints, inks, pencils and canvas/paper.  You can purchase low end items, but in the end the result comes from how well the item is made.  Price does not indicate value.

When you say there has to be more than that to it- it's more than what you think.  Personally, I've spent close to four hours on creating a specific morph for Michael 4 for example- if you want something specific the time is worth it.  Consider that for what you see in the marketplace on any 3D site.  It's not just the item that you're paying for....it's the vision behind it, the hard work put into planning it, making it, fixing what didn't work and making sure that the piece sent out for others to buy meets not only the maker's standards but everyone else's.

Dar