a solar sail with a number of cubesats as the payload.
with a lightweight payload, a solar sail could reach a significant fraction of the speed of light, letting a spacecraft make the journey to proximal centauri in six to eight years, within the lifespan of a robot probe.
CubeSats are small and light enough for several to be packed into a solar sail payload. the individual sats can be configured for separate tasks like imaging, field measurements, etc. perhaps with some extras for redundancy.
i think the cubesats would still need some sort of relay satellite to receive their transmissions and send them on to earth, but a large number of small satellites would allow the solar sail probe the flexibility multiple points of interest.