World Cup Champ Sydney Leroux -- Scores Perfect Wedding Gown ... FOR $10,000!!

Sydney Leroux is about to say "I do" in a wedding gown that shows off her killer physique for the low, low price of ... a $10,000 lace dress when she ties the knot in a few weeks.

The World Cup champ eloped with fellow soccer star Dom Dwyer earlier this year, but they're having a proper wedding celelbration in October. TMZ Sports has learned up-and-coming designer, Inbal Dror created a custom gown for Sydney.

Bridal stylist, Jessica Fama tells us Sydney decided on a mermaid style dress with a deep plunging neckline, and low cut back because she wanted "wanted to show her figure." We don't blame her.

Sydney and Dom have a high-priced track record -- as we first reported she designed a sweet $20k diamond wedding ring for him.