その建物は15000ドルはもちろんのこと、10000ドルでも売れなかった。

English Translation

The building was not sold for 10,000 dollars, let alone 15,000 dollars.

Tip: We don’t spell numbers like this.
15000ドル in Zenkaku should be replaced with

  • 15,000ドル in Hankaku with a commna, or
  • 1万5千ドル in Hankaku and Kanji combination, or
  • 1万5000ドル in Hankaku and Kanji combination

We prefer the second or third format when the number is very high (e.g. 日本の人口は、1億2千万だ。or 1億2000万だ。 = The population of Japan is 120Mn.)

Most of Japanese sentences on Tatoeba improperly converted numbers into Zenkaku. But they are just unreadable.