If I'm paying someone to do a custom logo for me, there better be a PSD included and I always ask up front. That way I can make simple changes and resize the logo, output it in different formats, use it as a watermark, etc etc etc.
Same thing when I'm paying someone for a custom script. I'm paying for the script, I want the source code in case I need to make bug fixes, or the programmer disappears I can have someone else make changes.
That's just common sense, and I won't use anyone that doesn't provide PSD or source file
