Your wait for more Adam goodness is nearly at an end, Deus Ex fans, because The Missing Link will be arriving next week, on October 18. The date stands for all valid platforms in North America, and Xbox 360 and PC for Europe, with the PS3 version arriving one day later across the pond.
As for pricing, folks on this side of the Atlantic can expect to pay 1200 Microsoft Points or $15 if they want to see more of Adam. In Europe, that's €11.25 for PS3 and €10.99 for PC. If you're in the UK, expect a £8.99 price tag.