Canon don't make such Neoprene case and "where to buy and how much" belongs to consumers corner, thread moved.
Op-tech make such neoprene case, you can find it in most major camera stores, our advertisers also selling generic neoprene cases, you can check out the mass sale section.
if you only keen to buy case with Canon words on it, I guess you can buy it from ebay since you able to find it from there.
hope this help.