Hmm, interesting question. I have not seen a set of hoses.
Whenever I have replaced hoses, I have gone to the local MB dealer. A number of the hoses are standard size that you just need a length of hose to cut from. In the States, we can get a 10% discount for being a Mercedes Benz Club of America member. The dealer should be able to pull the numbers for the preformed hoses (the upper and lower large radiator hose, the hose under the thermostat (a bear to get in), the hose with different size ends, the hose under the expansion tank (on the 250 SL and 280 SL, I think the 230 SL has a straight section) and the long heater hose (on the later 280 SL I think - from heater core to side of engine block).
It is usually a day or two delivery.