Auto auction is the cheapest place you can buy used cars in Japan.
If you register your account ,you can choose car from auction web site.

Moday Ju TOKYO・Honda TOKYO・Honda NAGOYA・Honda KANSAI・Honda FUKUOKA
Tuesday CAA TOKYO・Zip TOKYO・Ju SAITAMA・TAA KINKI・SAA SAPPORO
Wednesday Ju IBARAGI・Ju ISHIKAWA・CAA CHUBU・JAA・BCN・LAA SHIKOKU
Thursday Ju KANAGAWA・TAA KANTO・NAA NAGOYA・Ju GUNMA・HAA OSAKA
Friday NAA TOKYO・Ju CHIBA・Ju MIYAGI・Ju FUKUOKA・KCAA YAMAGUCHI
Saturda HAA KOBE・Ju GIFU・Ju NARA・TAA YOKOHAMA・IAA・ARAI OYAMA