I was trying to think of the HCV deals (which seem to me have been getting less lucrative). Was VRTX's acquisition of Virochem the last big (I know that's relatively but lets say > 100 million up front cash/stock)? I searched and it seems like it was just over a year ago (march '09) and they got $100 million cash and $275 million in Vertex stock.
I believe that's the last big HCV deal. Virochem shareholders got $100M cash plus 10.7M VRTX shares. VRTX stock was around 29/share at that time I believe, so that equates to about a $410M deal total when you add in the cash. I believe the Virochem compounds had completed Phase 1 trials as well at the time. I'm not saying it's going to happen of course, but look at ACHN sitting at a $90M market cap with Phase 1 PoC now for ACH-1625 (and ACH-2684 about to enter Phase 1 next year) and I think it's easy to see that there's at least the potential for some serious upside in ACHN. There are risks of course too.
It's easier to compare ACHN to the Virochem at the time of the VRTX deal than it is to compare IDIX given that IDIX has a lot more ongoing than Virochem did at the time and IDX184 is more advanced as well than I believe any of Virochem's compounds were.