Kasabian aren't that big in America compared to UK, but X Japan still have a fairly good spot in my opinion especially if the final act on that row is indeed AFI.
Lollapalooza isn't expensive at all for what you're getting. Based on the predictions, there are at least ten bands that I want to see and some of those acts (like X for example) charge a lot of money for their individual shows. X cost me $170 in Hong Kong and that was face value. Lollapalooza and other festivals are all about having an amazing weekend with lots of people, lots of bands and lots of fun.