The fastest and cheapest way is probably to make them yourself.
Otherwise look at the usual trading sites in your region and maybe you'll find yourself lucky 😀

Little side note, please don't try this with 80 ribbon cables. These will possibly add some data corruption as an undesired bonus.

This places claims to have some in 48cm and 90cm lengths: https://www.cabledepot.co.uk/ide-c-100_101.html

You can get jacketed flat cable like this: https://www.farnell.com/datasheets/910926.pdf but the prices may cause a minor coughing fit.