We use Attachment Mailer Plus:
HTML Form Manager, CGI Formmailer, Perl form script, form upload, file fupload.
They have several versions starting at $25. You could use something like FormMail, but the nice thing about Attachment Mailer (not just for attaching files to a reply form) is that it gets email addresses off the webpage and into a DB so there's less chance of harvesting. More secure.
James