One I can think of Torchlight for $5 - it has nothing ground-breaking, but it does everything almost perfectly. That is what some fellow gamers told me, as did the reviews. I am myself looking to buy it but I am having CC issues right now.
The Witcher enhanced edition at $13 is another VFM game IMO. Eidos Collectors pack is also extremely nice if you like the games in it. It is still $50 though. There is no substitue to browsing the games individually. Or you can wait for the daily deals - they are really bombastic. Torchlight is at the top spot ATM.