Poser is not VERRRRY expensive (unless you consider the time that you spend collecting freebies) since you only really need to buy Poser 6 itself. You get enough stuff with Poser 6 to start making interesting scenes and there are a HUGE number of freebies dotted all around the web (and of course in Rosity's large Free collection).
Also, DAZ3D recently made the Victoria 3 and Michael 3 base figures free (which the majority of Poser users probably use for their male and female adult figures), so the only add-ons that you might need would be the head and body morph packages. I would not recommend buying anything until you have had a play with Jessie and James, and all the other free stuff, and worked out what - if anything - you really want or need.
You will probably need your PSP 9 for a bit of Postwork to the renders (I personally didn't think the upgrade to PSP X was worth it for a slightly faster load-up).
Also, the quality of much of the free stuff is so good that you really do not feel like you are getting second best because it is free.
Using poser is quite easy when you get the hang of it, and there are sections of Poser that you might never need to visit (e.g. if you don't want to put your own photos on figure faces, if you don't want to dynamic hair - since the mesh based textured hair is great, if you don't want dynamic cloth, if you don't want to animate things) and you can grow into these techniques as and when you have the time.

This is roughly how easy it is to make a static scene in Poser:

1. In the "Pose" room, Use the library browser to select a "Character" figure (mesh) to load, e.g. "JamesCasual" from the "James" folder. I think the default is for this character to be loaded as soon as Poser starts.
2. Go to the "Material" room and use the materials browser to find the textures for your figure - this is like wrapping a photo of the surface around the mesh of the figure.
3. Go to the "Pose" room again and use the "Poses" section of the library which will probably have some poses for the figure to set it into a particular posture. Apply a suitable pose, e.g. James sitting at a meeting pose.
4. Go to the "Prop" section and add a prop for the figure to sit on, e.g. a cube primitive will do.
5. Select the charater figure hip using the pull down lists (or clicking on the hip) and move the hip-parameter dials for x, y, z so that the figure is sitting nicely on the cube. You might need to zoom out on the camera so that all of the box and the figure is visible.
6. Go to the "Material" room again and use the simple view to add a background image (e.g. a nice jpeg photo) to the "background" object.
7. ALWAYS, ALWAYS, Save your scene.
8. Go back to the "Pose" room and you can render the scene from the Render tab.
   There are also loads of tutorials available, e.g. from Dr Geep, who regularly posts here.
   Hope this helps.

OK, so I admit it, ... I am a POSERholic.