Ebay.com- Probably the most likely site to buy it from.
Unico In The Island Of Magic go as high as $50 sometimes! Theres plenty of hommade DVDs of
this going around, so be cautious when choosing who you buy from.
Animeglore
A few people have gotten the Japanese/English DVD from them with good remarks.
Amazon.com
Amazon may be able to special order it. Amazon
Japan sells it on DVD, if youre willing to pay shipping.