My advice is to learn how to make your own lights. There is no such thing as "one light set fits all scenes."  While IDL can look great, more often than not it ends up looking quite foney. I looked at the image examples for photobox and some of them just don't seem realistic too me. Aside for a serious lack of noticable shadows, I can't put my finger on what I don't like about some of them. The word "plastic" seems to come to mind.

Making your own lights allows for so much freedom and diversity. You can tailor your lights to give you lighting fitting for your unique scene.

Yes, there is a learning curve when it comes to learning lights. But learning lights in Poser 6 and up is so much easier than it was in Poser 5 where you needed upwards of 20 lights to achieve passable lighting.  In Poser 6 and up you can do it with as little as 3.  Some can manage with 1 light, but I've never been able to achieve anything nice with a single light. Usually I use 5 lights, but have used as few as 3 (2 IBL and 1 Spot).

When I set my mind to learning lights in Poser 6, I spent a good 6 months making images and focusing all of my efforts on the lights. As a result I now make my own lights for my images. I have a runtime full of light sets that I rarely use, and when I do use one, I use it as a starting point and tweak it to fit my needs for the image I'm using them in.

So really, the choice to buy is up to you.  However, I strongly recommend taking time to learn lighting.  I'm a real dummy when it comes to computers and programs, so if I can learn lights, anyone can.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi