Well I do everything myself except for an engine or trans rebuild and body work. Plus I know the W126 up and down and inside out. I can evaluate a used one and come up with a to do list pretty quick.
I really don't care what the blue book says about MB's. They are either way over like diesel W126's are way under like these cars, or W140's. My friend paid $11,500 for a W140 with a blue book value of $21k. In todays market that is considered only a "fair" price not a deal by any measure.
I see nice W126's languish on local lots for months on end.
So I find one with $6k on the windsheild that is in good shape. Offer $3k since it has been sitting for 6 months and has a few issues. Ignore certain things like AC because its a winter car, don't need that.
I bet I can get 4 years out of one with $1k in parts after the purchase and for a couple grand a year after that.
So $4k up front figure $1,500ish a year for parts, that would be $10k. After 4 years what would it be worth maybe $3k? So $7k lost. vs buying a $17k W140 with $5k down and a $12k 4 year note. hmmm interesting....