If this is a true one owner car.. I would think its a pretty good price. At 124K miles, I doubt anyone would call this a "high milage" benz. Just make sure that the timing chain and guides have been replaced. If not, these I hear would cost somewhere around $700 or so to replace. Then you would need to replace them every 100K miles. I would take the car to a mercedes benz dealership where they would to a PPI.. or an independent area mechanic that specializes in mercedes. The mechanic would probably tell you what these noises are and if they are serious. After doing so... I would then make my offer according to what the mechanic suggests. The 560 is the flagship mercedes for that year, and is also one of the strongest engines for a mercedes at the time of production. I have seen some people online that had way over 250K miles on their 560. So yes I do think that if the car is truely cared for, you will have many more miles on the engine before a rebuild. Good luck and let us know what happens!