If they added free returns within two hours you'd get people that would complain it wasn't three hours. There's no point in adding this because there willalways be someone that stupidly buys something they didn't actually want without doing any research. There's no helping these people beyond letting them screw themselves over and learning a lesson from it.

Just save your tomes until you're certain what you want to get. There's only one thing on offer per slot for your job anyway so it's not like it's particularly taxing to make a decision on.