Anything you can get close to the mid price now. Remember prices will drop before the weekend comes, so don't plan on holding up until the weekend happens. There are some things that might not drop, and some things that will drop but go up again right when the weekend starts, these would be last minute things people forget they need or stuff people buy after they are done with their primary goal. Maybe logs and raw food are in this category since people will decide to get the 10% bonus after they're done with herblore/smithing. Remember though, nothing is likely to rise much past 2x the normal price. What I mean by this is that if d-hides are 2k ea normal, they probably wont go far past 4k ea since up untill that point you would still save money by buying them, but after that point it is cheaper to wait and train with them without double xp when they can be bought for 2k ea again. Hopefully you understand what I mean by this.