I remember that one. Early 60s, ran for just a couple of years, starring Lori Martin and a big chestnut horse with a blaze. It was a very popular series even though it was considerably tweaked - quite different to the movie with Liz Taylor and also quite different to the original book. I don't think there are any legally available DVDs for sale anywhere, but according to one of my students, it's possible to watch the show's credit sequence, complete with musical theme, on YouTube. She said that she had the impression that either the person who put up the credits or one of the commenters (she wasn't clear which) was offering (probably bootleg) DVDs of the series. It might be worth investigating if you're curious. I don't know who has the actual rights to the series, but that might be worth investigating as well.
According to Wikipedia it aired from 1960-62, first season on NBC, and second season on CBS. It doesn't seem to be available from Amazon or other legitimate sources. Buying from other sources you have to be careful that the DVD is for your region, or it probably won't play. And as Sixteen said, it's on Youtube.