also, to show some security statements, you can force the coder to follow some rules when they code for you... the exact same way the coders may protect themselves by applying some rules:
http://nexialys.net/vbulletin/rules.php

also... "Modification Not Available?" is NEVER for paid job... unless the only solution is a paid modification.... never answer a first reply by accepting the job to be a paid one... wait for some days until someone can provide a free solution... and then if you have none, you can discuss a paid job.