gremcint

So having enjoyed Avernum 1 Escape from the Pit during the steam sale I bought the spiderweb bundle. However I see Avernum 3 is not included in the bundle at all, nor is it available on steam at all. Looking into it I see that you can only buy it by buying the 1-6 bundle on Gog. I'm not exactly happy about this, in fact I'm rather disappointed. So what do I do if I don't want to pay for the same games again? do I go ahead with Avernum 4? I know they're standalone but it's frustating to miss out on the story.