Probably because the new Star Wars movie Star Wars: The Last Jedi is coming out soon, the books about Star Wars universe have dropped in price quite a bit. So If you are a fan, then grab the opportunity and get yourself some books!
The Art of Star Wars: The Last Jedi for $19.55 (-51%)
Star Wars Art: Ralph McQuarrie for $128.79 (-48%)
The Art of Star Wars: The Force Awakens for $20.15 (-50%)
Star Wars Costumes for $31.19 (-48%)
The Art of Rogue One: A Star Wars Story for $21.75 (-46%)