I would advise buying the best condition 4.5 you can afford.
Heck, I bought my 4.5 from a forum participant, and it is a 3 owner car with every receipt since about 1980, and a hand-written log with every detail you can imagine.
It has not been spared a penny in maintenance and repairs.
About 10 years ago, it had a good quality repaint, and all new window seals installed. The trunk and hood seals are also new, including the side window and door seals.
I had the car inspected by two separate Mercedes mechanics, and it still had issues that neither inspection uncovered.
I paid $7,500 for it, and even with the few known issues and incredibly good condition, I've still put $3k-$4k in it, including rebuilding the power steering box/worm drive unit (leaked bad), re-coring the radiator, new axle half shaft and axle seals, new rear brake lines and emergency brake shoes, hydraulic cooling fan clutch, auxiliary electric fan, front brake pads, and front struts.
I also did a major maitenance service, including every fluid and filter in the car, and plugs.
So it goes to show you that even the best maintained and cared-for vintage Mercedes can still take a lot of money.
It's all part of the fun, and in the end, we do it for the love of the cars, for the enjoyment of driving them, and for the stories.
