Why the huge price difference?

Many Amazon prices are set by algorithms that try anticipate the highest price someone would pay. The LP would be that price because of things like a lot of searches and perhaps just one for sale (for example). The seller essentially ticks a box that is "get best price" rather than specifying a price directly. Amazon's algorithms and data analysis then gets to work.

The obvious answer is that vinyl sounds that much better than CD or MP3 .

It must have been a very limited LP release. These are sometimes as low as 500 copies. Current price on Discogs for said LP is $321-$556. Said CD on that same site starts at $0.35.

Greed! 

buy a chord mojo instead of a USD 900 LP.

crazy.

https://www.discogs.com/sell/release/580371?ev=rb

This is a valuable pressing, it's worth about 300-500 bucks. The amazon listing is over-priced but not by an order of magnitude. 

Thanks for this, i have found the „piece by piece“ in my collection.