php preg_replace()

Hi,

Im having problems with this piece of code. I need it to replace special characters with "". It is doing it for the first 5 $punc variables listed below but it does remove the $ for some reason. Anyone have an idea why its not working for this character?

Thanks

[PHP]
//insert the article slug
$my_listing_url=strtolower($business_name); // transform to lowercase
$punc[0]="/!/";
$punc[1]="/\"/";
$punc[2]="/£/";
$punc[3]="/'/";
$punc[4]="/€/";
$punc[5]="/\$/";

// add any punctuation marks likely to be used in your title

$my_listing_url=preg_replace($punc,"",$my_listing_url);

// replace all instances of any punctuation found in the $punc array with ""
[/PHP]