I would be careful about buying everything at once. I've only just gotten back into card making and stamping about 6 months ago, and my ideas about what I like and my style have changed quite a bit already :-).
I like using by distress inks with the daubers or ink blending tool to mark the edges of paper or die cuts, or create a background on plain card. I had a lot of trouble using it for embossing though, so I went for the versamark watermark ink. The Ranger Perfect Medium works well too (I got a small pad with my perfect pearls).
I bought Versafine in black for stamping sentiments, and Stazon Jet Black for stamping on shiny cards (it even worked on the lid of my altered Milo tin).
I do plan to pick up more distress inks in the future, but I think I'll use them for backgrounds etc. I originally saw them all demonstrated at the local craft expo. If you're not sure, see if you can take a couple with you to a class and get them demonstrated. Then buy more of the type you think you'll use the most.