Hi,
For the Porsche, expect to spend about 3500 - 5000 USD per year on maintenance and upkeep, namely suspension parts, tires (it eats them), brakes (they are very pricey parts) and if the divider gearbox is trashed (which it is usually on those - then expect another 3500 in parts and then about another 1000 in labour. It also has some interesting porsche specific failures like the coolant manifold connection between the banks, that job alone is a 20 hour job to replace. Other than the above, generic maintenance like filters etc are doable but expensive to procure and install too.
The W211 benz is a nice car but the 4 cyl engine is rough and noisy - it also has some interesting failures but I tell customers to make an accrual account of about 2000 - 3000 / year to cater for wear and tear (suspension parts, brakes, tires, AC, and other small maintenance items)
The S class is like owning 2 E classes together, it has way way more gizmos packed into it and has unique parts like air suspension massage seats which means more stuff to maintain. All of its parts are pricey no matter where you buy them from and its labour cost is higher because there is a lot more to work with.
The Lexus LS460 AWD is a very nice car but remember that its a flagship car of toyota and doesnt use generic toyota parts, but bespoke parts made for this car only, meaning its about the same damage as owning an S class benz or BMW 7 series. It wont require too frequent maintenance if you are on top of it,
All in all - do not buy the above unless they are in proven top notch condition, if you purchase a basket case with engine damage or completely shot suspension or an electric gremlin then expect to pay through the nose which may exceed the value of the car and plan for extreme downtime too.
Anyway - good luck, I like driving mercedes benz vehicles and have owned several E classes on which I have travelled coast to coast on. Its about how you keep your vehicles, some people want an appliance vehicle which doesnt ask much like a Corolla, while some do actually take care of their equipment.
