SOLD Short answer: No. Longer answer: Maybe.
Cars like this 2005 Mercedes-Benz S55 AMG have come down from their sticker price - way down. From an original MSRP in the $120K range, examples like this can be had for 10 cents on the dollar - a pretty amazing supercar bargain, considering its features and performance - 492HP from a supercharged 5.4 liter V8, 0-60 in 4.5, a quarter mile in the mid 12s, skidpad like a Corvette, and a host of luxury, safety, and convenience features. This is an amazing car.
But can the everyday guy afford to own it without breaking the bank? Probably not, or certainly not while maintaining it to concours levels. The biggest offender is the standard ABC sport suspension system, with costs running in to the multiple thousands. Other systems aren't quite as expensive, but can still nickel and dime you to death.
That said, there are some ways that it can be done, with a little bit of luck and taking an active role in repairs and maintenance. Firstly, starting with a good example is essential, as many of the things that break on these cars will already have been addressed. Secondly, having a good mechanic that you know and trust will help keep costs down, as an unscrupulous shop will take advantage of an owner who doesn't take the time to know what things should cost. And finally, knowing what to fix and when to fix it will help defray the cost of ownership - for instance, if the door closing assist stops working, just close the door a little harder until you can feel comfortable spending the $1100 to repair it. If you've got a little valve cover leak that's not dripping on the exhaust or ground, let it ride for a while until you're addressing some other leaks on the car, and do it all together. Using your brain and having a strategy will go a long way toward keeping ownership costs down.
Below is a list of some of the maintenance and major repairs on these cars, and what the (retail) cost of fixing them would be at a fair shop:
Maintenance
Servicing every 10k miles
A Service: $250
B Service: $700
Spark plugs at 80-100k miles (16 of them): $500-600
Transmission flush every 60k miles: $400-450
Repairs
ABC System:
Replacement struts (per wheel): $1000-1100
Replacement Pump: $2000
Replacement pressure line: $1000
Oil Leaks:
Valve cover gaskets: $800
Rear main seal: $1200
Other repairs:
Supercharger pulley replacement: $700-850
PSE (vacuum) pump: $600-700
Transmission conductor plate: $800-900
Shifter electronics rebuild: $600
How much or how little of the repairs you have to do depend on the prior maintenance of the car, how it's driven, and luck. Whether it's worth the risk or not to drive a car as incredible as the S55 AMG is a decision only the buyer can make.