s/(?<=[a-z])-(?=[a-z])/ /g;

##</code><code>##

my %replacement;

$replacement{'\$34\.50'} = '$17.25';
# ... key is match, value is replacement

for my $item ( keys %replacement ) {
    s/$item/$replacement{$item}/g;
}

##</code><code>##

my $replacements = 
 [
   ['S\&O 400', 'S&P 500'],
   ['\b400\b', '200'],
#   ... (or read these match/replace literals from a file)
 ]

# this provides a stable, consistent order of application

for my $edit ( @$replacements ) {
    s/$$edit[0]/$$edit[1]/;
}