Well first, if NOT spending money is the highest priority, NEVER buy a new car, and look at historically GOOD vehicles with which to draw on your used vehicle purchase. With that said, I feel that the cheapest to operate cars in Volkswagen, Toyota, and Honda camps have already come and gone.
For Volkswagen I'd say the A2 platform cars, in particular the German-built ones since back then there were issues with US and Mexican built cars (which is no longer the case). These cars are simple, tough, reliable, easy to service, and parts are easily obtained at a reasonable cost. Since VAG built these cars for so long and marketed them globally, and STILL continues to build an updated A2 Jetta in China, support for these cars will be around for a long time.
For Toyota, the second generation Camry with the 3S-FE 2.0L 4 cylinder or any 4A-FE equipped Corolla ('90 through '97) would be my top picks. Only real problem with those cars is rust, but since both were HUGE sellers in their day you can still find solid examples out there for a reasonable price. They are super reliable, easy to service, and even if you refuse to use both feet to drive still offer a good long-lasting autobox.
For Honda, any fuel-injected Civic pre '96 will be a good reliable car, and the lesser models with a 5 speed can get TDI-rivaling fuel economy to boot. These also offer a nice sporty drive, surprisingly roomy behind the wheel which is something many Asian cars lack, and the enormous sales mean you can easily find them. Rust, as usual, is always an issue.
