I don't buy new books often, so I don't really know what he market is. Used Dresden Files books ranged from $4-12 delivered for the most part. I generally get hardbacks, but they didn't exist until Dead Beat and for some reason, I ended up with Cold Days, I think, in paperback. You can get Skin Game for about $8.50 right now, used and hardback. New it's over $30. Paperback for about $9 something, new or used. (All Amazon).
Amazon is telling me $18.31 for the Peace Talks hardback. So that's about $10 for getting it soonest and in mint condition (unless your delivery guy throws it over your gate, RobReece). I only see the kindle edition for Battle Ground. Barnes and Noble is coming out to $41.16 total for both for me. Free shipping, didn't check tax, but I'm sure that's added. I'm figure the Battle Ground hardback will be about the same as Peace Talks once it hits Amazon.