Costs $5, and I think they are the best Slim cases around. Cheaper than Spigen or Ringke slim cases. Was going to recommend them but I've heard Spigen & Rignke cases give you scratches on the corners (see the reviews).
amCases are cheaper but I did not own this one so I cannot say with certaincy. I've tried the Spigen case and I like it. Bumpers are all around the corners so your phone will survive a drop.