This article is from the FAQ, by with numerous contributions by others.
Varies widely, but quotes here in Los Angeles were:
$1500 due upon approval of petition
$1200 covering both fiance(e) visa *and* eventual green card
**note**: approval of the petition does not complete the process of
obtaining a fiance(e) visa!! The fiance(e) must still be interviewed
and approved by the consulate.
 
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