I can buy things, but when I click on the item that is for sale, something is activated. I am in creative mode and it acts like I am about to edit the item or sale--maybe? Whatever is trying to happen, it keeps crashing me out of the game. I have no idea if this is from your mod or a different mod is interfering, but these are 2 crash reports from me doing the same thing: right click on an item in a shop.

crash-2016-11-22_20.06.18-client.txt
crash-2016-11-22_20.22.04-client.txt

This is caused by NoMoreRecipeConflict. Trying removing that and see if it solves your issue :)

Problem solved! But I guess nothing was even trying to happen, though. How do I modify shops, then?