"Rosshaarspinnerei, Gummihaar und schaumpolsterfabrik” (horsehair sprayed with a rubber material)

Decomposing horsehair seat pads...

I'm looking for a cheap solution for replacements on the W116. Best price I've found for the back seat was $170 for the bottom and $197 for the back cushion. Local upholstry shop wants close to $1k to re-cover front and back seats. I just need to find a cheap alternative.

From what I can tell the original pad was formed to fit. I'm thinking foam replacement won't be firm enough.

Tips, suggestions...