It depends on spec and quality if the car. They are an extremely robust car, but you still need someone that "knows" them to look at one if you are interested. They are a 'Hull/Chassis', where all the body panels are just decorative and can unbolt. This Hull needs to be rust free. You can't tell this from pictures of the outside. The usual giveaway is the boot area (they had a big sponge boot seal that soaked up water and held it against the boot opening almost indefinitely once wet).
The market for classic cars has really softened over the last couple of years. The covid hysteria has passed in the classic car market. If I was in the market for a nice DS it certainly would be worth a drive to look at it.
You do understand the youngest Citroen DS is now 50years old. Its not a modern daily driver, that will never need to be looked at between services.
They are just a lovely old car. It will be noisy and hot in summer ... and noisy and not hot in winter (heaters are ok).

