PARIS — Millionaires now have their very own multimedia shopping channel on French TV. One of the first items offered is a stately French chateau dating back to the 13th century, a giveaway at a mere $3 million.But you don’t have to be a millionaire to watch Wishline, launched this week by French theme channel owner Multithematiques, a subsidiary of Canal Plus. Director Gilles Galud said Tuesday: “You are allowed to watch it even if you’re not rich. In fact we have two targets, people who wish to see amazing things, and people who can buy them.” The interactive channel, which broadcasts in five languages, airs free to CanalSatellite subscribers in France, on D Piu in Italy and on Astra in Germany. Viewers in Spain, Poland and Scandinavia will receive it in 2000.