Imagine rovers collecting samples on Mars and launching them to dock with a Mars-Earth transfer spacecraft. This vehicle would be in a Mars cycler orbit which passes near Mars and Earth every 7 years, for example. The sample in a cubesat sized probe and put in Earth orbit, possibly landing on Earth. It could also carry terabytes of data in solid memory chips brought together with the rock samples from instruments on the surface of Mars. All being low weight and cheap to accelerate, using the fuel stored in the Cycler.
The point would be to lower mass and complexity of the Mars ascent vehicle, so that for each return to Earth only one Atlas V class launch, or so, would be required to land it on Mars. Plus the one time larger launch of the reusable cycler. The cycler could provide fuel for Earth orbit insertion of the sample, and during the transfer also solar power, shielding, Earth communication, keeping the samples at Mars temperature if desirable. And maybe a capsule for direct Earth landing (storing one for each return mission foreseen). A sample return mission once every third conjunction (about 7 years) doesn't seem overly ambitious.
Could sample ascent, Earth landing and cycler transfer vehicles be made light enough to make this feasible today? Or would they need too much overhead equipment? Would the high velocities required for rendezvous with a cycler orbit eat up the benefits?