I charge $25/hr. Period. Including the time it takes for Poser to do the render. If you want edits/additions/changes, I charge for that time as well (unless it is clear I ignored something in the original instructions.) I give them an esitmate for the time (subject to revision), and require half up front.

If the client wants something I don't have on hand, I certainly go get it... whether the client gets to pay for it depends on whether or not I think I'll ever use the item again. If I'm going to charge them for it, I tell them up front.

I'm still waiting for the first complaint.