In sqlstyledtable.php:

  1. find the line of code which takes the price from the database result and puts it into a variable
  2. create a new line under that one and  paste in this: if ($cdPrice<=5) {$highlightclass=" style=\"color:green;\"";} else {$highlightclass="";}
  3. make sure there is a space before style but after the quotes
  4. a line or two below that you should already have the $rowclass variable inside some quoted HTML - add a space then $highlightclass so there are two variables now

The if statement is on one line but otherwise is a normal if statement (change it if you prefer it on multiple lines).  It creates a variable which is either empty or contains a style attribute (it would probably be better to use a class like before but this works as well).  That will then be output to the page by the amended echo line.  When you try it any cheap CD should be shown in green rather than the default colour.  You could make them bold or style them in other ways.  If you do not have a cheap CD it will not work!