In response to this question, I was told that the Elysian Whip can be bought from the online shop. Unfortunately, I'm using an emulator. Can you still access the online shop from there?
When playing using an emulator it does not appear that the online shop is accessible. It appears that the only way to access the online store is when playing the original game or using a flash cartridge.
In your case the Elysian Whip will not be accessible to you. Sorry about that.