If php regex is anything like perl (which I guess it is as it was "copied")... then your syntax is wrong.
I'm not sure why you need ( ) though seeing as you aren't doing anything with the match.
Code:
if (!preg_match("/([0-9a-z ]{1,$max_title_length})$/i",$Price)) {I'm not sure why you need ( ) though seeing as you aren't doing anything with the match.