title: Regex failing when pattern involves dollar sign ($)
body: <p>I'm running into a bit of an issue when it comes to matching subpatterns that involve the dollar sign.  For example, consider the following chunk of text:</p>
  
  <pre><code>Regular Price: $20.50       Final Price: $15.20
  Regular Price: $18.99       Final Price: $2.25
  Regular Price: $11.22       Final Price: $33.44
  Regular Price: $55.66       Final Price: $77.88
  </code></pre>
  
  <p>I was attempting to match the Regular/Final price sets with the following regex, but it simply wasn't working (no matches at all):<br>
  <code>preg_match_all("/Regular Price: \$(\d+\.\d{2}).*Final Price: \$(\d+\.\d{2})/U", $data, $matches);</code></p>
  
  <p>I escaped the dollar sign, so what gives?</p>