There was a 124 CD set on eBay last week, for about $50.00 US, not sure if still there or how high it might have gone. Caution about the eBay CD's, you might be getting an illegal copy.
If you have enough in your budget, you could get a new CD set right here at PartsShop for $159.00.
Hope this helps.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.